**Unsustainable Development: A Case Study of Urban Planning History and Pandemic Trends in the United States**

**Warren S. Vaz**

#### **1. Introduction**

Human population has undergrown explosive growth, going from under a billion in 1800 to almost 8 billion today. Many factors enabled this growth, but it is categorically unsustainable given that it happened in about 10–11 generations. Indeed, thanks to the actions of several governments in the 20th century, many countries have stabilized or even reversed this trend. As technology continues to improve our lives, the amount of resources an individual consumes only continues to increase. Take energy consumption as an example. According to BP's review (BP 2021), global energy consumption has gone from 5653 terawatt-hours in 1800 to 173,340 terawatt-hours in 2019, a factor of over 30. Juxtaposed with a population growth factor of just under 8, it can be concluded that per capita energy consumption has increased and can be projected to continue to increase for a number of reasons. People are using more devices than ever. Modes of transportation are getting faster: high-speed rail, supersonic planes, space travel, etc. The proliferation of the Internet, Big Data, and cryptocurrencies are other powerful factors. Further, huge swaths of the global population are still underdeveloped. This can be expected to further strain the limited resources of the planet as their energy demands catch up to the rest of the developed world.

It is not just the sheer numbers but also the distribution of the growing population that must be studied. There are many ways to categorize population distribution. For this study, the degree of urbanization, i.e., the percentage of urban population, is most relevant. According to the United Nations (United Nations 2018), global population urbanization has gone from 7.3% in 1800 to 54.4% in 2016, and this is projected to be 60% by 2030. While modern cities are reaching unprecedented sizes and pushing the limits of infrastructure, studies conducted in several countries (China (Dong et al. 2018), United Kingdom (Arbabi and Mayfield 2016), United States (Center for Sustainable Systems 2020)) concluded that as the population density increases, per capita energy consumption decreases. Urban centers are definitionally much more densely populated than rural areas. People live closer

to work, recreation, and each other, and have to consume less energy to travel. Urban transit adds an additional level of efficiency. Additionally, governing and providing infrastructure and logistical services to such agglomerations is less-energy intensive than if spread over thousands of square kilometers. This does not mean that modern cities are examples of sustainability. City dwellers, in general, tend to consume more resources than their rural counterparts. Car ownership, meat consumption, and the use of multiple appliances are all higher in cities than in rural areas, particularly in developing countries. Torrey (2004) identified several studies that highlighted the patterns of consumption between urban and rural areas. While it is true that cities, in general, are also responsible for a larger portion of wealth generation, they also tend to waste more resources. If cities are not planned correctly, it can lead to unsustainable development that causes inefficient use of resources and unnecessary pollution and waste. Thus, despite the benefits of proximate living, pollution becomes more concentrated, leading to worsening air quality (Wang et al. 2018) and the urban heat island effect (Liu and Zhang 2011). With humanity facing the unprecedented challenge of climate change (IPCC 2019), the time to act to build a more sustainable future is now.

Not all cities are created equal. This study takes a close look at urban development in the United States (US). The US is one of the oldest countries in the world and has the oldest continuously used constitution. The changes in cities from the colonial period through the various pivotal points in US history are examined. Key demographic shifts and their impact, prompted by or spurring changes in public policy and sociological factors, are outlined. The challenges with public policy and funding in a Federal system of government are used to explain how urban planning was impacted. Here, the unsustainable nature of these policies, both in terms of the environment and the economy, is explained. Besides the author's affiliation with the US, there are several reasons why this country provides an instructive and important case study. The US has historically been a world leader, by some measures the only current superpower. It led innovation and invention in several related fields: manufacturing and transportation (road, rail, shipping, air, and space). It is the largest in the world by gross domestic product (GDP), second by total energy consumption, third by population, and fourth by area. It controls and sets trends in several critical sectors. It is regarded as a world leader and tends to lead the way in decision-making and setting policy globally. It has the largest military, and its military spending exceeds the next ten highest countries combined. It also is one of the largest consumer markets in the world, especially for energy, not just by total but also per capita.

The annual primary energy consumption in the US is estimated to be 26,300 terawatt-hours. Numbers differ based on sources. Per capita it is about 80 MWh/y (BP 2021). The only countries with a higher value are small, oil-rich countries such as Bahrain and Qatar. Canada is the notable exception, being right above the US in world rankings. Canada's economy is as developed as the US, but its climate is a lot colder. Indeed, the climate type and economic development are better indicators of energy consumption than the degree of urbanization. In the US, when looking at the energy consumption versus the degree of urbanization on a state level, the correlation coefficient is only 0.31. Figure 1 shows the correlation for 131 countries with available data (US Central Intelligence Agency 2021; International Monetary Fund 2021; The World Bank 2021). The *R* 2 -value between per capita energy consumption and urbanization is 0.2503. For per capita energy consumption and per capita GDP, it increases to 0.3373, indicating a stronger correlation.

This study is meant to serve as a brief review of urban development in the US throughout its history, particularly focusing on its unsustainable nature. The next section provides a brief historical overview to provide context for the observations of Section 3. This section highlights various hallmarks of urban design and planning. The results and issues caused are also discussed with selected examples and case studies from 2021. Section 4 discusses how the COVID-19 pandemic was the catalyst for changing the historical trends. Finally, some perspectives on modern urban planning and solutions to remedy the highlighted issues are provided in the final sections.

**Figure 1.** Correlation between per capita energy consumption and (**a**) urbanization; (**b**) per capita GDP. Source: Figure by author, data from US Central Intelligence Agency (2021); International Monetary Fund (2021); The World Bank (2021).

#### **2. Urban Development in the US**

#### *2.1. Historical Overview*

Urbanization in the US has steadily risen since the country's founding: under 7% in 1790 to around 40% in 1900, rising sharply from about 56% after World War II to about 73% by the 1970s, and climbing steadily to about 82% today (Boustan et al. 2018). The postwar increase is especially notable given that the total population of the country also grew from about 140 million to about 200 million in

that same period. To understand the underlying factors, it is important to understand the country's history.

The United States declared its independence from colonial rule in 1776. Like its neighbors, Canada and Mexico, the United States adopted a Federal government with strong state governments. Critical sectors such as transportation are funded and regulated by all levels of government. Concomitantly, in many critical sectors and situations, there is no central authority to provide a unified decision or course of action. In its early years, the US was not globally recognized as a nation for several years. Several established nations still viewed it as a potential colonial acquisition. Most importantly, the entire territory of the first 13 colonies was east of the Appalachian Mountains, north of Florida—about 11% of its extent today. Gradually, several territories were acquired, organized, and formalized as states—territories east of the Mississippi, then the entire Mississippi River basin (Louisiana Purchase), the Oregon Territory, Florida and the Republic of Texas, and Spanish Territories all the way to the Pacific Ocean. Finally, Alaska and Hawaii were added as states in 1959 almost 50 years after Arizona. Several of these regions were, and to some extent still are, very sparsely populated.

Since before the birth of the nation, settlers engaged in importing African natives as slaves to work on large, cash crop plantations—corn, cotton, tobacco, sugar, and rice—in southern states, where the climate and soil enabled such practices. By contrast, the economy of the Northern states was predominantly predicated on agriculture and industry. Innovations in manufacturing and transportation technology—such as the steam engine—propelled the rise of factories and factory workers, with several Northern states abolishing slavery in their territories. Southern fears over the abolishment of slavery in the Union led to the Civil War, which culminated in the permanent abolishment of slavery in the United States in 1863 and the defeat of the Confederacy of Southern States in 1865.

After the war, the conditions in the South degenerated for virtually the entire population. Black Americans, a minority, were now free and full citizens of the Union. However, their White counterparts, some of whom were their former slaveowners, enacted various measures to deny their rights, keep a stranglehold on political power, and restrict their access to education, land ownership, etc. Sharecropping and the Jim Crow Era in the South ensured segregation on the basis of race. Simultaneously, unable to profit from free slave labor, several White landowners, including women, had to work the land themselves—a hardship not previously endured.

Meanwhile, the new territories in the West continued to grow and develop at the expense of the native population, who were continually pushed further west.

Immigrants, especially Chinese laborers, contributed to the proliferation of the railroad and steam locomotive, which helped to connect the country and spurred the prodigious rise of American industry. The total track length progressed from about 60,000 miles (96,000 km) to about 160,000 miles in the 1890s with the completion of the Transcontinental Railroad. This figure peaked during World War I (254,000 miles) and is about 140,000 miles today (Stover 1999). Some of the most iconic and enduring American companies were founded during the latter half of the 19th century and the early 20th century: Standard Oil (later Marathon, ExxonMobil, BP, and Chevron), General Electric, AT&T, Emerson Electric, Carnegie Steel (later U.S. Steel), Ford, General Motors, etc. The vast majority of these were headquartered and had most of their operations in Northern states.

After World War I, there was a period of booming economic growth in the country. The transportation section grew, with major innovations in aviation, automobile technology, rail (e.g., diesel locomotive), and shipping. Then came the Great Depression, followed by the New Deal, a series of major economic and infrastructure reforms aimed to spur the country out of the Depression. World War II continued to drive the growth of the massive American industrial complex accompanied by a surge in population, the "baby boom". The Interstate System that was signed into law during the war made road travel easier than ever. Continued incidents of racial violence, voter suppression, the rise of the Ku Klux Klan, lynching, segregation, etc., prompted a mass exodus of millions of Black families from the South to the North and West. Coupled with continued immigration, several cities such as Philadelphia, Detroit, Chicago, Cleveland, Baltimore, and New York City saw a huge increase in their population and a change in their demographics. This lasted roughly from 1916 to 1970. On the other hand, after World War II, thousands of veterans left the cold harsh winters of the North and migrated to the Sun Belt states. Cities such as Los Angeles, San Diego, Las Vegas, Dallas, Houston, and Phoenix also grew significantly.

During this period of urbanization, a pattern began to emerge: the gradual movement of large populations from city centers to small satellite towns and communities within close proximity, commonly called suburban development or the suburbs. Spurred by legislation such as the Federal Home Loan Bank Act of 1932 and the National Housing Act of 1934 along with contributions from the Veterans Administration, families were able to buy homes in newly developed areas outside cities. No longer did they need to live in cramped, densely packed apartments in crowded, polluted, and noisy city centers. The United States transitioned from a primary economy (natural resources) to a secondary one (manufacturing). To travel to these well-paying jobs in the cities, workers bought increasingly affordable cars, one of the most important products of this new economy. The total number of miles of paved road continued to increase, especially between cities.

Thus, what happed was that the traditional city centers absorbed the majority of the Black and immigrant population, while most of the middle-class White residents flocked to the suburbs. City centers declined overall despite the new Black residents, because they were, and still are, a minority demographic. Under the National Housing Act, the Federal Housing Authority (FHA) created several guidelines and minimum standards for new housing developments. Unfortunately, it also strongly promoted racial segregation in its guidelines. The design of suburbs focused on car-friendly, wide streets and left out pedestrians. Instead of grid plans, curved and dead-end or cul-de-sac designs were adopted. These were designed to slow cars down and limit traffic through streets but also ensured that cars were necessary to get around. The FHA rated any designs submitted within these guidelines as "good plans" and the rest as "bad plans", making it riskier for developers to pursue. Suburbs grew, their design made walking and public transit inefficient, and existing public transit systems in the city centers fell out of favor and became neglected. The people who depended on these systems the most had little power to influence their improvement. Even if Black families wanted to move out of the city centers, 'redlining' made it impossible for them to secure affordable housing (Lynch et al. 2021). The Fair Housing Act of 1968 put a gradual end to this practice, but the intervening decades had done their damage. Whole generations of minority populations were unable to build wealth via home ownership. Similarly, minorities were also denied access to education and political power with suppression of voting. It was only after the Civil Rights Acts of the 1960s that some of these practices slowly began to decrease. Still, the country is recovering from these effects to this day.

Figure 2 shows the explosive suburban growth for two major cities in the US that have grown the fastest over the last 100 years: Houston, Texas; and Phoenix, Arizona. Note that the population of the counties including and surrounding the city in question is shown based on the best available historical data. The natural logarithmic scale is used to allow for easier discernment of the color scheme. The Houston area grew by a factor of 32 and Phoenix by 69. By comparison, Beijing and Mumbai, two of the largest cities in the world, grew by about 10 and 20, respectively, during the 1910–2020 period. Despite this, inflation-adjusted per capita GDP from 1910–2020 grew by a factor of 29. This phenomenon took place across hundreds of cities in the country. Thus, the United States arrived at the situation in which it is today: declining urban centers surrounded by sprawling suburban development.

**Figure 2.** Growth of urban and suburban regions for (**a**) Houston and (**b**) Phoenix; population in natural logarithm scale corresponding to 13,299 to 4,698,619 for Houston and 9045 to 4,485,414 for Phoenix; blue circle is location of city center in the state (US Census Bureau 2021b). Source: Figure by author.

#### *2.2. Methodology*

The approach used is based on the historical context provided. A comprehensive, literature-based argument is used to highlight the characteristics and effects of urban development in the US. Two guiding principles were the influence of Federal policy and economic factors. In addition to satellite map data, Federal (FHA 1956; Code of Federal Regulations 2001) and state (Wisconsin Department of Transportation 2017) traffic planning documents were consulted.

The results are examined from a standpoint of environmental impacts and economic impacts. Accordingly, four categories are examined. How each one influences the other is explained. Given the size of the US, emphasis is placed on common factors that are typical of the urban United States. Case studies from 2021 are used to support the analysis and glean important insights. Similarly, recent developments related to urban development resulting from the COVID-19 pandemic are discussed, along with key legislation that is aimed to stem the ill effects of poor urban planning in the US. The aim is to provide an overview of where the country is headed in the years to come.

#### **3. Unsustainable Development: How Policy Shaped the Present**

Armed with some historical perspectives and insights into the critical legislation that steered it, this section highlights why urban development in the suburban US is unsustainable. While urban development is a complex topic, the leading factors are explained here:

To demonstrate how one factor leads to the next, certain case studies will be used to provide examples. While the US is a vast and diverse country, traveling from state to state makes for a surprisingly uniform and familiar experience, especially when it comes to modern cities and the interstate system.

#### *3.1. Population Density and Suburban Layout*

#### 3.1.1. Land Use—Single-Family Zoning

Even though the US is the third largest nation by population, it is the fourth largest by area, and so it is not surprising that it is listed at 185th out of 250 countries

and territories recognized by the United Nations (United Nations 2018) when ranking population density. According to US Census Data (Ruggles et al. 2021), the average household size decreased from 5.79 in 1790 to 2.63 in 2018. Given that the overall population has grown, this implies the number of houses occupied has increased at a much higher rate. Fewer people are living in any given house. However, this alone does not explain the low population density in the country. In the US, the vast majority of housing falls into two types, single-family homes and mid- to high-rise complexes. The term "missing middle" (Wegmann 2020) has been used to define the kinds of housing—duplexes, rowhomes, courtyard apartments, etc.—that used to be more common, especially in older cities before World War II, but are less common now. Zoning policies make it virtually impossible for developers to build anything other than single-family homes in most suburbs. A side effect is that limited land and increasing demand drives up housing prices almost everywhere (Picchi 2021). In cities such as Minneapolis, Minnesota, about 70% of residential land is reserved for single-family housing. In San Jose, California, it is 94%. The average home in the United States grew in size from 1500 sq. ft. in the 1970s to over 2000 sq. ft. nowadays (Friedman and Krawitz 2001). Interestingly, the average lot size has continued to decrease as pressure for suburban housing continues to increase.

#### 3.1.2. Case Study of Kimberly, Wisconsin

To illustrate why American suburbs are huge and sprawling, consider the example in Figure 3. A residential block in the village of Kimberly, Wisconsin is shown. The term "village" is an administrative designation and is used to describe suburbs around large cities, in this case, Appleton, with a metropolitan population of 236,000. Kimberly's population is a mere 6800. The area between Emons Road, Main Street, Calumet Street (major arterial road linking to US Highway 10/Highway 441), and Eisenhower Drive is approximately 200 acres (0.8 km<sup>2</sup> ). It comprises mostly single-family houses, with a handful of apartment complexes, typically two- or four-unit developments. Note that non-residential buildings are virtually nonexistent. Some restaurants and businesses are located to the southwest. That section is part of the larger highway exit development discussed later. There are about 350 houses. Using the average per household of 2.63, that gives 920 residents. For a conservative estimate, take it as 1000 residents. The population density comes to about 1125/km<sup>2</sup> , which is close to the census value of 1143/km<sup>2</sup> . For comparison, Manhattan in New York City is 26,821/km<sup>2</sup> and Brussels is 7400/km<sup>2</sup> . It is clear that such residential development makes highly inefficient use of land. In the figure, observe the large stretches of open space that are not used. While Americans enjoy

their yards, in Figure 3, most of the green space is unusable. It does not belong to the individual homeowner, is not developed for public use, and does not connect to any roads or walking trails. Usually, this space is inhabited by wildlife, but being so close to humans and roads, animals often end up being killed. Plus, it costs time and resources to maintain it: landscaping around the edges, pest control, runoff, etc. There is one park in the middle, but again, it can only be easily accessed by road. The distance from the yellow marker at the end of the cul-de-sac Stillwater Trail is 500 ft (152 m). However, due to the street layout, to avoid walking through private property and undeveloped land, one must walk about 0.5 mi (0.8 km). It is the same situation to access any of the businesses, the main road, or even a neighbor's house. In almost all cases, a five-minute walk is replaced by a car trip.

Figure 3 **Figure 3.** Residential block in Appleton, Wisconsin. Source: Google Maps (2021c)—Kimberly, Wisconsin, @ 44.26, −88.34.

As mentioned before, these suburbs are very unfriendly to pedestrians and cyclists. There are no dedicated lanes for cyclists and no sidewalks in the neighborhood shown. This is a consequence of housing and zoning policy: building

Figure 4

3

around nature rather than integrating nature into the design. Older cities in the US and several other countries integrate green spaces, trees for shade, and other public spaces for leisure or outdoor dining into the neighborhood's design and layout without compromising accessibility. These typically include low- or no-traffic streets and buildings that are multi-use: businesses on the lower levels and residences on the upper levels. All of these are located within a short walk from public transit. This is the basic idea behind the "15-minute city" (Clerici Maestosi et al. 2021).

#### *3.2. Highways, Roads, and Streets*

#### 3.2.1. Definitions of Roadway Types

The Interstate System in the US is fairly uniform across the country: two lanes in each direction with entrances and exits having additional dedicated merge lanes. The *highways* (freeways) are mostly straight and flat with virtually no stopping—a huge improvement from the US Highway System that they were meant to replace. There are universal signs for fuel, food, rest stops, etc. The speeds vary from 65 to 75 mph (105 to 120 km/h). These speeds generally drop to 50–60 mph when passing through a city. There is usually a minimum speed as well, 40 mph (64 km/h). By contrast, most *streets* (local roads) passing through residential neighborhoods, such as the ones within the four named borders in Figure 3, have a speed limit of 25 mph (40 km/h). Several of these may not have sidewalks, STOP signs, or even lane markings.

Now consider the *roads* (arterials or collectors) that connect highways to neighborhood streets, such as the four named border roads in Figure 3. These typically vary in speed from 35 to 55 mph (56–88 km/h). These generally have traffic lights, STOP signs, yield signs, or traffic circles (roundabouts). These roads connect highways to streets and are usually lined with non-residential buildings. Not only can traffic execute turns at intersections, but several states have reversible lanes (US Department of Transportation 2020), as shown in Figure 4. These allow either side of the road the right of way. Once in the lane, the driver has to turn left across two lanes of oncoming traffic. For these reasons, they are colloquially called "suicide lanes". The main efficacy is to allow traffic to turn left whenever desired without slowing down the entire road. This also obviates the need to construct a median. The median between interstate highways can be up to 60 ft (18 m) in width and is essentially wasted space. Concrete barriers are also placed within city limits and a reversible lane eliminates the need for such additional material.

Figure 4 **Figure 4.** Reversible "suicide" lane with yellow lane markings as the centermost lane of US Highway 141. Source: Google Maps (2021e)—Reversible Lane, @ 44.49, −87.97.

#### 3.2.2. Problems with Roads

Figure 3

3 Roads are inefficient at moving traffic and extremely hostile to cyclists and pedestrians. US intersections prioritize the movement of cars through intersections, meaning pedestrians have to wait a long time and might be tempted to jaywalk. Dedicated cyclist lanes are either absent or within immediate proximity of fast-moving traffic, leading to frequent collisions and fatalities. With cars frequently and unpredictably turning out of or into the road, other drivers have to slow down or completely stop, even with the reversible lane. In addition to being dangerous for cyclists and pedestrians, roads are also dangerous for cars. According to the US Department of Transportation (US Department of Transportation 2020), the average annual rate of traffic crashes per 100 million vehicle miles traveled is as follows: interstates—0.48, arterials—1.1, and local streets—0.78. Arterial roads are by far the worst.

#### 3.2.3. Case Study of Phoenix, Arizona and Appleton, Wisconsin

In Figure 4, on either side of US Highway 141, between the road and the pedestrian sidewalk, green medians are present. These are designed to provide distance between pedestrians and fast-moving traffic, which would be unnecessary on a local street. This is wasted space and adds to the unwalkability of suburbs. To illustrate this, consider Figure 5, a typical suburban intersection—this one is a busy location in Phoenix, Arizona. The intersection has six lanes, three in each direction. The approximate distance for a pedestrian to make the crossing is 120 ft (36.5 m). The residential portions are, once again, not connected to this intersection in the most direct way, forcing residents to take a meandering route, which encourages them to drive.

**Figure 5.** Intersection of 43rd Avenue and Thomas Avenue is a residential neighborhood of Phoenix, Arizona. Source: Google Maps (2021d)—Phoenix, Arizona, @ 33.48, −112.15.

In Figure 6, a busy intersection in Appleton, Wisconsin, is shown. This locality is immediately to the west of the area in Figure 3. A hypothetical walking trip is shown in yellow in Figure 6a. Note the absence of dedicated cycling lanes, forcing cyclists to either share the road with cars or the sidewalk with pedestrians. For someone living in the neighborhood to the bottom-right (Victorian Drive), a walk to the fitness center (Anytime Fitness) in the north necessitates crossing the intersection, which is 148 ft (45 m) because of the number of lanes and medians. Then, the person goes to Kohl's, stops by Culver's for a meal, followed by Walmart, and back home. This simple trip is 1.7 mi (2.74 km) and would take almost 40 min to walk (accounting for stopping at intersections, but not accounting for the actual visits). Just walking from Kohl's to

Walmart is 1284 ft (391 m). Clearly, this is because of the huge parking lots, which dominate the entire business plaza in Figure 6b—in addition to all the unused green space. This is another reason for huge suburb sizes: in addition to single-home lots, useless green space, and wide roads, part of the zoning laws previously mentioned contained guidelines about the minimum parking lot size. This has resulted in oversized lots that are vacant most of the time. Some estimates indicate that 70–80% of downtown parking is vacant (Florida 2018). In Seattle, there are 5.2 spaces per household. In Des Moines, it is 19.4. In New York, with one of the highest transit populations in the country, it is 0.6. The nearest public transit stop in Figure 6, Valley Transit bus service, is at Walmart. Thus, the whole Town of Buchanan, which is to the east of Eisenhower Road, is completely devoid of any public transit. Residents would need to walk a mile to catch a bus to Downtown Appleton. Such development makes walking all but impossible. It must be iterated that, in the US, the Interstate system and collector-feeder system are fairly uniform across the country. While certain historic downtown areas in city centers have one-way and car-free streets, the sheer size of urban sprawl necessitates the design features of roads and parking lots articulated here.

#### *3.3. Unsustainable Development, Unsustainable Finances*

#### 3.3.1. Low-Density Development and Suburban Insolvency

The land area of Phoenix is 519 sq. miles (1344 km<sup>2</sup> ). However, the metropolitan area is listed as 14,600 sq. miles (37,814 km<sup>2</sup> ), similar to Bhutan. Houston city is 571 sq. miles, but the metropolitan area is 10,062 sq. miles. For comparison, Rome, with a comparable population, is listed at 500 sq. mi (1295 km<sup>2</sup> ). This is important because the way land is designated by governments directly affects how it is utilized and taxed. Residents within city limits expect certain amenities, infrastructure, utilities, etc. The city is obligated to provide these at the same cost to all. Naturally, if the population density in a given area is very low, then the tax revenue will also be low. However, the cost and energy requirements to build and maintain the same level of service are not the same. It costs significantly more to build roads, dig sewers, lay utility lines, etc., over 14,600 sq. mi than over 500 sq. miles. Maintaining green medians, resurfacing parking lots, patrolling sprawling suburbs, responding to emergencies, etc., exerts a significant financial toll on the limited resources of municipalities, not to mention the planet. A dense, multi-use district brings in much more revenue than a parcel of land such as in Figure 6, where there is one business with 75% of the land dedicated to parking. Figure 4 is no different.

**(a)**

**(b)**

**Figure 6.** Intersection of Calumet Street and Eisenhower Drive in Appleton, Wisconsin: (**a**) hypothetical walking trip in orange; (**b**) parking lots in yellow. Source: Google Maps (2021a)—Calumet Streeta, @ 44.24, −88.34.

The precarious finances of suburban developments can be explained as follows. Due to the Federal nature of government, funding for roads comes from all levels of government. Cities typically provide about a quarter, Federal funds account for another quarter, and the state departments of transportation provide the rest (US Census Bureau 2018). So, cities are incentivized to build new roads because they do not have to pay very much and they generate new tax revenue. However, the cities do have to pay to maintain that infrastructure. At the end of the new road's lifespan, suddenly the city is on the hook for a massive bill. This is typically masked by revenue from new development—recall that US cities such as Houston and Phoenix are recording double digit growth rates. Thus, suburban development becomes a Ponzi Scheme, with the maintenance of old developments being paid for by new developments. If property tax revenue, the main income source for cities, cannot cover road maintenance, sewage systems, water treatment systems, fire and police services, schools, parks and public spaces, etc., the city becomes insolvent.

#### 3.3.2. Effect of Parking Infrastructure

There are numerous examples and case studies of bankrupt cities and municipalities in the US. What is undeniable, is that this low-density, car-centric development comes at a steep cost. Americans, especially in the suburbs, are used to free parking. In New York, the public cost per household for one parking space is USD 6750. In Seattle, it is USD 117,677 and, in Des Moines, it is USD 77,165 (Florida 2018). By legislating parking minimums, local governments are subsidizing parking lots at the taxpayer's expense. The Federal income tax exclusion for commuter parking allows employees to exclude USD 250–255 per month for qualified parking received from their employer from taxable income. Estimates vary, but at 10 spots for every car in the US, the country spends between USD 100 and 374 billion on parking. It is a public subsidy that only serves those who can afford a vehicle. It exerts a health toll by encouraging driving and prohibiting cycling or walking and, by extension, causes more avoidable deaths—not to mention pollution. Moreover, the more people drive, the more they want investment in car infrastructure and that leaves less for public transit.

#### 3.3.3. Examples of Suburban Insolvency

Highways are efficient and safe compared to roads and streets. Streets are necessary. Roads, on the other hand, are dangerous and inefficient—even 45 mph is a relatively high speed, necessitating wider lanes (11–12 feet), longer turn and merge lanes, signaled intersections, etc. This often comes at the cost of other infrastructure. Public Works in Tampa, Florida, for example, created a plan to repair aging infrastructure that would cost USD 3.2 billion over 20 years. Tampa currently spends an eighth of that, about USD 20 million per year. It plans to pay for this by phasing in higher rates over several years and taking on a lot of debt, about half the total expected cost. Notably, just two departments, water and wastewater, already spend USD 28 million on debt payments (City of Tampa 2021). Tampa's geography will be especially taxing on its aging water infrastructure: with an elevation of 48 ft

(14.5 m) above sea level, rising sea levels could prove catastrophic. In the city's history, 68 hurricanes and tropical storms have passed within 60 mi (96.5 km). Most recently, Hurricane Charley caused USD 16 billion in damages in 2004. Given the 80–100-year lifespan of water infrastructure, these expensive repairs could not have been a surprise for the City of Tampa. Further infrastructure-related bankruptcies that are listed for further reading include: Stockton, California; Harrisburg, Pennsylvania; San Bernardino, California; and Desert Hot Springs, California.

#### 3.3.4. Effect of the "Gas Tax"

Another commonly employed measure to remain solvent is to secure a bailout package from the State or Federal government. Americans expect modern, high-service infrastructure, but they are not willing to pay for such infrastructure. Suburbs look nice, but they are unhealthy financially and for the environment. This issue permeates even at the national level. It was mentioned previously that Federal funding accounts for about a quarter of highway funding. This Highway Trust Fund (HTF) is principally funded by fuel tax on gasoline, diesel, and kerosene as well as sales and use taxes for heavy vehicles. In the 1960s and 1970s, over 70% of the construction and maintenance cost of US highways was covered by these driver fees and taxes (Dutzik et al. 2015). The "gas tax" has not been proportionately raised to keep up with inflation and rising costs. From 4 ¢/gallon in 1960, the tax was raised to 9 ¢/gallon in 1983, 14.1 ¢/gallon in 1990, and 18.4 ¢/gallon in 1993, where it has remained. Note that states can levy their own tax, ranging from 14.4 ¢/gallon in Alaska to 86.9 ¢/gallon in California. These do not contribute to the HTF. The gasoline tax, just keeping up with inflation, would be 33 ¢/gallon today. Due to this shortfall, the HTF is projected to have a negative balance by 2022 unless policies change.

Figure 7 shows the breakdown of US freight by mode of transportation. Global shipping is dominated by rail and maritime transport. In the US, however, truck shipping is competitive with rail because of the tremendous subsidies for the auto industry, including depressed fuel prices and taxes. Besides the parking exclusion mentioned above, the sales tax exemption for gasoline purchases in several states is another way the burden of paying for roads is shifted from drivers to all taxpayers. Governments spend more non-user tax dollars on highways than on transit, cycling, and walking combined (Dutzik et al. 2015). Larger vehicles cause more damage to road surfaces. With a load limit of 80,000 lb (36.3 tons), the damage inflicted by a loaded semi-truck compared to a 250 lb cyclist (cycle and cyclist) is about 10 orders of magnitude greater (Dutzik et al. 2015). It is estimated that trucks pay only 50–80% of the costs that they extract from highways via user fees, the rest coming from

other drivers and non-user general tax monies. This is how trucking is effectively subsidized and remains competitive in the US.

**Figure 7.** US freight breakdown by mode of transportation. Source: Figure by author, data from US Department of Transportation (2019).

#### 3.3.5. Effects on Social Equality

To come full circle, it is instructive to take a look at the object surrounded by this unsustainable infrastructure: the single-family house. US median home prices have risen from about USD 125,000 in the early 1990s to USD 350,000 in 2021. With mortgage rates lower than ever, borrowing money to buy a house is relatively cheap. Because of high demand and zoning laws, which prohibit multi-family housing or units above a certain height level, developers are disincentivized from building starter houses. Rather, they opt for more expensive homes that afford greater profits. This is not helped by the requirement to set aside land for parking as well. Starter homes have dropped from 40% of new construction to less than 7% (US Census Bureau 2021a). According to Freddie Mac (Federal home Loan Mortgage Corporation), while the homeownership rate in the US hovers around 70%, it is only 43% among Millennials (Freddie Mac 2021). Given that, historically, the most common way to build wealth in the US was owning a home, the current generation is missing out. This does not even address the huge gap between various ethnic and minority groups. It need not be repeated that the main reason for exclusionary zoning was the desire to keep the suburbs racially segregated.

#### *3.4. Decaying Infrastructure*

Politicians and elected leaders have a narrow time horizon. Infrastructure projects require long-term planning. The US had a first-mover advantage, leading the world in rail, telegraph, telephone, airport, electrical grid, and road construction. However, given the complex Federal–state–local funding mix, updating this infrastructure has proven difficult, making it old, unreliable, and prone to failure. Successive administrations are used to plugging holes. Even at the community level, getting funding and approvals requires cooperation between several agencies at different levels, municipalities, residents from multiple communities, etc. Residents seldom support tax increases to pay for infrastructure. People overestimate the value of present conveniences and are more concerned with present pain than future agony (Jacquet et al. 2013). Consensus is often elusive, so action is delayed or deferred. The following recent case studies illustrate these complex forces in action.

#### 3.4.1. Case Study of the Texas ERCOT Grid Failure of 2021

According to the Department of Energy, 70% of the grid's transmission lines and transformers are over 25 years old and the average age of power plants is 30 years (Gerrity and Lantero 2014). Neglect and deferral lead to decay and failure. The most recent and prominent example of this was the failure of the Texas electrical grid in the winter of 2021. Most of the State of Texas (second largest by area and population, about 30 million) is part of the Electric Reliability Council of Texas (ERCOT) Interconnection (Figure 8), which, by design, limited the amount of electricity it could import from neighboring states. Then Winter Storm Uri struck. About 10 million residents were left without electricity for several days. Temperatures were below freezing, breaking records in several places, in a state with little experience dealing with such temperatures. About 111 deaths were recorded (State records only show 14, but some sources cite as high as 705) and about USD 155 billion in economic losses were estimated for the country (Busby et al. 2021). This was primarily because Texas failed to winterize its grid after smaller-scale events in 2011, 2003, and 1989. This was followed up by another close call as recently as June 2021. To date, Texas regulators have not said why 12 GW of generating capacity was offline when demand was dangerously close to the peak of about 70 GW. Residents were asked to reduce consumption to avoid a total blackout.

**Figure 8.** Non-ERCOT counties of Texas (orange). Source: Figure by author.

#### 3.4.2. Case Study of the Hernando de Soto Bridge in Memphis, Tennessee

What can only be described as another close call was the closure of the Hernando de Soto Bridge (Bing Maps 2021). This bridge is a part of Interstate 40 and bridges the Mississippi River as it enters from Arkansas to Memphis, Tennessee, as shown in Figure 9. The bridge is almost 50 years old and carries about 50,000 vehicles per day as it is a major freight corridor. A routine inspection in May 2021 found a one-inch crack across one of the box beams of the main deck. This beam is an arch tie, responsible for withstanding the tension exerted by the truss as it tries to straighten out under the bridge load—this is similar to how a bowstring keeps a bow in tension. The bridge was closed and repaired before opening to traffic in July-August (Burnside 2021). A 2019 inspection was investigated, and drone footage of the bridge revealed significant damage in the area where the crack eventually formed, leading to the inspector responsible being fired.

**Figure 9.** Hernando de Soto Bridge; inset map of Memphis, Tennessee shows the bridge in a red box. Source: Microsoft product screen shot reprinted with permission from Microsoft Corporation: Bing Maps (2021), @ 35.15, −90.06.

According to a comprehensive study (ARTBA 2021), a third of US bridges, about 220,000, need repair work, with almost 80,000 needing replacement. At the current rate of work, it would take 40 years to complete this. It is impossible to assume that in every single case, critical defects will be found in time for repair. On a related note, Figure 9 (inset) shows another problem with the US highway and road infrastructure. They are designed to move people from the suburbs to the city center. They do not connect neighborhoods in various suburbs to each other very well. Consequently, public transit maps mimic this phenomenon. The main highways through Memphis are I-40, I-55, and I-69. The bypass highway, I-240, circles the city, forming a rough square of 8 mi (12.8 km). I-269 forms an even larger bypass ring through the outer suburbs, as far as Hernando, Mississippi, at 22 mi (35 km). To demonstrate the issue, take Southaven as an example. From Southaven to Downtown Memphis is 13 mi and takes about 13 min. From Southaven to the neighboring suburban town of Olive Branch is 12 mi, but this journey takes 22 min—there is no major highway, just smaller roads. Considering these towns have a combined population of over 90,000, this makes for very inefficient road travel between the two.

#### 3.4.3. Case Study of the Surfside Condominium Collapse

The Surfside condominium collapse happened in Surfside, Florida, about 16 mi (26 km) from Miami. On 24 June 2021, Champlain Towers South (Figure 10), a 12-storey building, partially collapsed (Frisaro and Calvin 2021, p. 40). The official

death toll was 98, with several dozens injured and rescued. The building was about 30 years old. As part of its 40-year recertification, inspections as early as 2018 found issues with water seepage in the concrete slab above the parking garage. This likely expedited the corrosion of the reinforcement steel. Since this pool deck slab did not directly support the building, there were likely other factors at play, such as uneven land subsidence putting additional stress on the building's foundations. All these factors were known before the collapse and a USD 15-million plan had been approved before the collapse, but no structural work was being performed at the time of the collapse. As a result of a county-wide audit that followed, multiple buildings were closed off and evacuated due to structural concerns. There have been several other notable public infrastructure failures in the US since 2000 alone. Examples include the breach of the canal levees in New Orleans due to Hurricane Katrina in 2005 and the I-35 Mississippi River Bridge collapse in Minneapolis in 2007.

**Figure 10.** Champlain Towers South (orange box), located in Surfside, Florida. Source: Google Maps (2021b), @ 25.87, −80.12.

#### 3.4.4. Discussion

The Texas grid failure was a direct result of decades of state government policy deliberately aiming to isolate most of the state from cooperative interconnects. This is a result of a lack of Federal regulations that would mandate such redundant safety systems—a common theme in various government sectors in the US. The other two case studies, Hernando de Soto and Surfside, are best explained by general neglect of infrastructure, which is pervasive in various cities across the US. As

mentioned previously, the time frame of political cycles and general unwillingness of citizens to pay taxes commensurate with the level of infrastructure found in US cities lead to such disastrous outcomes. Recent events have sparked a gradual change in the mindset of policymakers, as is explained in the following section.

#### **4. COVID-19 Pandemic and Future Trends**

The 2019 coronavirus disease (COVID-19) pandemic posed unprecedented challenges to the US as a whole. Besides the health and economic tolls, the US was the epicenter of significant political and social unrest as well. The pandemic brought into focus several of the historical issues that have been presented in this article: racial segregation, wealth inequality, and government policy directly affecting infrastructure planning. Compounding these challenges were the unprecedented effects of climate change: extreme drought in the West that continues to this day; severe wildfires in 2020 and 2021; Hurricanes Isaias, Laura, and Sally in 2020; Hurricanes Claudette, Fred, and Ida in 2021; multiple tornadoes; severe weather events; hailstorms in the Midwest and South; multiple heat waves; floods; and extreme freezing events (NOAA 2021). These have caused several deaths, even more injuries, and billions of dollars in damage. Water scarcity continues to stress farmland in several states.

#### *4.1. Migration Trends*

There are powerful forces simultaneously driving people to and out of cities. Urbanization has increased by about 0.2% every year since 2010. California and Oregon have had thousands of residents displaced due to fires and ensuing evacuation orders. Louisiana has lost residents living in coastal communities due to rising sea levels. On the other hand, in July 2021 alone, the US Border Patrol reported about 200,000 encounters with migrants at the US–Mexico border. These people migrate for a number of reasons, but climate change was a big factor: Hurricanes Eta and Iota, occurring within days of each other; and the instability of the Dry Corridor, spanning vast areas in Guatemala, El Salvador, Honduras, and Nicaragua. Due to the immigration status of several migrants, exact statistics are hard to obtain. What is clear is that the majority end up in urban areas (McConnell 2008), especially in California, Texas, Arizona, and Florida.

With pandemic lockdowns and working from home being a common refrain in 2020–2021, Americans increasingly moved out of big cities. The fear of social unrest only added to this tendency. There were many factors, but some common ones stand out. The most obvious one was the desire to remain away from population

centers during a pandemic driven by an infectious disease. With the closure of campuses, factories, and most of the leisure industry, several individuals moved in with parents or extended families. With millions on furlough or without work, simply being unable to afford expensive housing in and around cities was a major factor. Working from home temporarily or permanently meant people did not have to commute to work, so living close to work was not necessary. Several families sold expensive homes in and around large cities and bought larger homes in cheaper states—to accommodate working from home or just carry out more activities at home, including schooling. About one in five Americans either moved or knew somebody who moved during the pandemic (Cohn 2021). The cities that were the biggest gainers were Sacramento, California; Las Vegas; Phoenix; Austin, Texas; and Atlanta, Georgia. The biggest losers were New York City, New York; San Francisco, California; Los Angeles, California; and Washington, DC (Anderson 2020). This migration has been strangely reminiscent of the Jim Crow Era and Postwar Era: some demographics moving to cities and others away. Recessions typically tend to reduce mobility and vacation spending. However, during the pandemic, expensive vacation destinations saw a huge increase in population. West Palm Beach, Florida, saw an increase of over 62,000 with a 2019 population of just 112,000. Over half of pandemic job losses were in low-wage sectors, so this is not surprising: wealthier individuals moved because they had options.

#### *4.2. Industry Effects*

What can be broadly concluded is that the pandemic has continued to disperse the US population, with people investing even more in their homes. These trends have had direct impacts on several related markets—furniture, home improvement, lumber, swimming pools, etc. Another notable trend is the bicycle boom, particularly in the US, where several states had lenient lockdowns and permitted outdoor activities. People also chose to bike to work to avoid crowded public transportation. An approximately 50% increase in cycling traffic was noted in 2020 relative to the same period the year before in New York City. Several metro areas modified traffic patterns and opened more roads to increased numbers of cyclists and pedestrians (Dowell and Hait 2021). In analyzing data from multiple countries such as the US, Canada, Belgium, France, Germany, and the UK, it was found that cycling for recreation and exercise increased while cycling for transportation to work and educational facilities declined. Biking infrastructure was expanded and improved. Simultaneously, car traffic was restricted through various measures such as restricting access to certain streets and reducing speed limits. These were possibly due to the

pandemic (Buehler and Pucher 2022). The "bike boom" is predicted to stay, but it is unclear whether it will translate into a long-term transportation alternative. Just a few days into lockdown, March 2020, the average daily travel distance in the US plummeted from 8 km to 1.6 km (Hendrickson and Rilett 2020). Virtually all sectors of transportation declined, from public transit to personal trips to leisure travel. This had a knock-on effect on fuel consumption, air pollution, traffic accidents, etc. Conversely, the demand for transportation and logistics in e-commerce and certain consumer staples surged, sometimes leading to shortages in certain goods. With global supply chains disrupted, the "just-in-time" method of inventory has been questioned going forward.

#### *4.3. Infrastructure Projects and Future Changes*

The weak public transit infrastructure in the US has been even more severely tested by diminished ridership during the pandemic. The CARES Act (March 2020) and CRRSAA Act (December 2020) provided USD 25 billion and USD 14 billion, respectively, for public transit. Pandemic protocols such as increased cleaning and disinfecting, physical distancing, and reduced ridership due to working from home are expected to continue to exert financial stress on operating costs, leading to a projected USD 39 billion shortfall through the end of 2023 (APTA 2021). With state and local taxes declining due to overall diminished economic activity and fuel tax revenue also declining due to fewer vehicle miles traveled, public transit budgets face additional challenges from those brought on directly from revenue loss. This is expected to compromise capital spending.

The sea change that was the COVID-19 pandemic has ushered in a new era of change, something that had been building for several years. The City of Minneapolis almost unanimously passed its ambitious Minneapolis 2040 Comprehensive Plan that ends single-family zoning, eliminates citywide parking requirements, and aims to create a more connected urban experience, among several other goals (City of Minneapolis 2018). All this was in response to the rapidly increasing population, increasing pressure on the housing supply, and historical racial disparities. In 2019, the aforementioned Houston is slowly ending mandatory minimums for parking, allowing developers and business owners to decide—this is currently only in a couple of neighborhoods, but it is a start (Brasuell 2019). Currently, states such as California and Massachusetts are considering housing reform, but this issue remains highly divisive.

With lockdowns in place and traditional sources of leisure and entertainment closed or operating with greatly reduced capacity, people spent more time in urban

green spaces. The general attitude of the public towards the importance and use of such spaces improved as a result. In several cities, restaurants were allowed to operate with outdoor dining. Even after pandemic restrictions were lifted, some of these changes became permanent. Cities are beginning to increase investment in such spaces, with a view towards equity, as minority communities typically lack access to such spaces. Researchers have proposed models such as Barcelona, the "green block" modeled after the "superblock" (Burrowes and Schilling 2021).

Potentially significant is the Infrastructure Investment and Jobs Act introduced in early June 2021 (IIJA 2021). If successful, it will provide about USD 1 trillion for various infrastructure issues: new safety requirements across all transportation modes, a program to rebuild rural bridges, mitigate climate change and the impacts of the transportation systems including enhancing its resilience, and most relevant to this article, public transit investment—repair and upgrade bus and rail fleets, improve accessibility, reduce inequity, provide service to new communities, and reduce the carbon footprint of transit vehicles. Even before the pandemic, several public transit projects were in progress or set to start: rail link between San Jose and Santa Clara in California; light rail projects in Boston, Los Angeles, San Diego, and Seattle; electric buses in Indianapolis' rapid transit system, etc.

Light vehicle sales continue to reflect the trends discussed earlier in this work: an aging population with the bulk of the wealth concentration, urban sprawl with increasingly expensive homes requiring vehicles to perform even basic tasks. According to Kelly Blue Book sales data, the number of midsize sedans sold in 2020 was about 50% of what it was in 2012. Light vehicle sales constituted 27.3% of all car sales in 2019 (third quarter). This fell to 24.2% a year later and 24.1% in 2021 (first quarter). Thus, the majority of light vehicle sales in the US are crossovers, sports utility vehicles, pickup trucks, and vans. Before the 2008 Financial Crisis, the split was the opposite: about 45% cars and 55% everything else. Luxury vehicles accounted for approximately 14% of all light vehicle sales just before and during the pandemic. Expectedly, the average transaction price of a new vehicle continues to trend upwards: from USD 35.5 thousand in 2016 to USD 42.2 thousand in June 2021. While automakers have relied on efficiency improvements and hybrid technologies to meet fleet-average emissions regulations, several major manufacturers, including General Motors, are planning for all-electric fleets by 2035. The current Federal government has emphasized electrification of the Federal fleet, a good way to lead by example. This means the conversion or replacement of some 645,000 vehicles, comparable to the annual emissions of countries such as Haiti or DR Congo. Once the Federal government takes the lead, state and local governments will follow. Consumers are already adopting electric vehicles, making it easier for automakers to make the necessary investments.

#### **5. Perspectives on Modern Urban Planning**

It is easy to understand the state of urban planning in the US given the historical, political, and technological context. The newest cities, ones developed after World War II, and their suburbs could have been designed differently. However, single-family zoning, redlining, car-friendly layouts, vast parking lots, and inefficient roads produced the environmentally and financially unsustainable suburbs of today. There are many studies that have investigated some of the issues raised in this work. In (Fiack et al. 2021), 22 of the 100 largest US cities' climate adaptation plans were analyzed. At the local level, social equity and climate adaptation were more prominent relative to economic development. Particular concern was shown for marginalized populations. Another study found that zoning does cause inequality and exploding housing costs but indicated that more work is needed to link the co-evolution of zoning across large metro areas and suburbs and how that has shaped demographic changes (Shertzer et al. 2021). A study in Buffalo, New York, specifically looked at pedestrian collisions at intersections with the goal to build a more walkable city. Vulnerable populations were given special focus (Yin and Zhang 2021). Plans to build pandemic-resilient cities in England, Germany, and Italy found that intracity connectivity was more important in disease spread compared to intercity connectivity. City morphology also had an impact, with linear cities being more resilient than grid or radial plans (AbouKorin et al. 2021). The recommendation was to improve the public transit efficiency quickly, before people switched to private vehicles. For a comprehensive treatment of the problems with urban planning in the US in particular, Duany et al. (2010) may be consulted as a starting point.

#### **6. Closing Remarks**

The Kardashev Scale is a method to gauge a civilization's technological mastery. The metric used is energy. A Type I civilization is capable of harnessing all the energy available on its planet. Though not perfect, the ability of humanity to harness increasing amounts of energy over time has roughly aligned with technological progress: from wood to coal to petroleum to nuclear. The impact of explosive growth has been so severe that this era of geologic time has even been named the 'Anthropocene Epoch', characterized by increases in population, energy consumption, and GDP (Syvitski et al. 2020). However, the resources for this planet are finite, so

efficiency is key to maximizing wellness. Furthermore, humanity has discovered that technological progress must be made whilst keeping the health of the planet in mind.

This study provided a brief historical overview to explain the state of urban planning and urban sprawl in the US. Key features of US cities and suburbs were discussed. These include restrictive zoning laws, car-centric city and suburban design, poorly structured roads, a lack of public transit options, etc. The low population density puts tremendous strain on infrastructure and leads to unsustainable finances for several municipalities. This, in turn, leads to neglected and derelict infrastructure, several examples of which were highlighted. COVID-19 has challenged the status quo and, in many ways, catalyzed future change.

The US has been a pioneer and leader in transportation and several related industries. For a more sustainable and environmentally friendly future, initiatives such as the ones highlighted—relaxing zoning laws, repairing roads and bridges, and investing in clean transportation—will be required. These must go hand in hand with the push for clean energy and social justice. Cities within the US can serve as examples of good urban planning, especially plans from before the proliferation of cars and urban sprawl. Globally, cities such as Copenhagen and Singapore are good examples of smart urban planning: promoting mixed-use housing, cycling and walking, and robust mass transit systems. Finally, urban planners in developing countries with growing populations and industrial centers can learn valuable lessons and avoid repeating the mistakes of the past.

**Acknowledgments:** The author would like to acknowledge the inspiration, ideas, and examples of Jason Slaughter, host of the YouTube channel on urban planning Not Just Bikes (https://www.youtube.com/c/NotJustBikes).

**Funding:** This research received no external funding.

**Conflicts of Interest:** The author declares no conflict of interest.

#### **References**

© 2023 by the author. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).


*Article* **Optimizing Expected Shortfall under an** *-***1 Constraint—An Analytic Approach**

**Gábor Papp 1, Imre Kondor 2,3,4,\* and Fabio Caccioli 3,5,6**

4

	- Complexity Science Hub, Vienna 1080, Austria

**Abstract:** Expected Shortfall (ES), the average loss above a high quantile, is the current financial regulatory market risk measure. Its estimation and optimization are highly unstable against sample fluctuations and become impossible above a critical ratio *r* = *N*/*T*, where *N* is the number of different assets in the portfolio, and *T* is the length of the available time series. The critical ratio depends on the confidence level *α*, which means we have a line of critical points on the *α* − *r* plane. The large fluctuations in the estimation of ES can be attenuated by the application of regularizers. In this paper, we calculate ES analytically under an -1 regularizer by the method of replicas borrowed from the statistical physics of random systems. The ban on short selling, i.e., a constraint rendering all the portfolio weights nonnegative, is a special case of an asymmetric -1 regularizer. Results are presented for the out-of-sample and the in-sample estimator of the regularized ES, the estimation error, the distribution of the optimal portfolio weights, and the density of the assets eliminated from the portfolio by the regularizer. It is shown that the no-short constraint acts as a high volatility cutoff, in the sense that it sets the weights of the high volatility elements to zero with higher probability than those of the low volatility items. This cutoff renormalizes the aspect ratio *r* = *N*/*T*, thereby extending the range of the feasibility of optimization. We find that there is a nontrivial mapping between the regularized and unregularized problems, corresponding to a renormalization of the order parameters.

**Keywords:** portfolio optimization; regularization; renormalization


*3.2. Tokenization*

Each review in the data set is individually processed. The preprocessing of the reviews starts by the tokenization phase that splits a piece of review into small units such tokens. A typical tokenization process can confiscate punctuation marks from the given text and create tokens of the text. A token can be anything, a word or a symbol, etc. Here, we use Core NLP PTB Tokenizer which is actually PENN TREEBANK way of tokenization of English writing and it splits the reviews into sentences in order to make a simple review file.

#### *3.3. Stop Words Removal*

A set of meaningless or irrelevant words in a piece of text can seriously affect the accuracy of the output. Hence, removal of such stop words from the input text is an important phase in sentiment analysis of the text. In the collected user reviews, a stop word can be a number, a preposition or a person's name, a product's name, etc. Each review after tokenization goes through the stop words removal phase. The used approach uses Core NLP library [33], which helps in identifying a list of stop words.


**4.6 Perception of Workload of agriculture activities**

Physiological cost of operation is influenced by the health of operators, nutrition, basal rate and energy expended while working which will be indirectly measured by measuring oxygen consumption and pulse. Generally, person's subjective experience of a specific workload or rate of labor is more closely associated with pulse than to oxygen consumption during the performance of labor. Therefore, several research workers [48–52] have used pulse for assessment of physiological workload of the workers. [22] Indicated that farm women perceived significantly lowered exertion while performing the chosen farm activities with the improved tools compared to the utilization of traditional tools. According to this study [53], the impact of drudgery on women is that many respondents suffer from heavy physical strain and physical stress due to work overload i.e. 88.34 percent and 98.34 percent in Tarai and hill area. In addition, fewer respondents have the problem related with incidence of miscarriage i.e. 10 and 12 percent in Tarai and hill.


**3.1.6 Depression**

Depression has been reported to be a predisposing factor for delirium in the elderly (Elie et al., 1998) and in non-cardiac surgical patients (Dasgupta and Dumbrell, 2006). The reduced functional connectivity in the human brain which is associated with depression (Anand et al., 2005) was hypothesized to be one of the mechanisms that predispose depressive patients to delirium (Sanders, 2011). On the other hand, the authors of the data synthesis commissioned by the National Institute for Health and Clinical Excellence (NICE) reported

The most common of delirium in hip fracture patients were reported as drugs that have central nervous system effects, infections, fluid-electrolyte disturbances, metabolic/ endocrine disturbances, intracranial processes, cardiopulmonary compromise and/or drug

Medical comorbidities such as burns (Palmu, 2011), cancer (Bond et al., 2011), cardiovascular disease (Branco et al., 2011), and alcoholism (Pompei et al., 1994) are among the predisposing factors for delirium. Sensory impairments like visual impairment and functional dependence also predispose individuals to delirium (Burns et al., 2004). In a study investigating a multifactorial model of delirium etiology, a predictive model was formed and 4 predisposing factors were identified for delirium: vision impairment, severe

Having a severe illness and staying in intensive care unit are also predisposing factors for delirium. Delirium has been reported in up to 80% of critically ill patients (Ouimet et al., 2007). Delirium is an independent predictor of adverse intensive care unit outcomes, including increased risk of death, longer hospital stay, and higher costs (Ely et al., 2004;

Male gender was found to be a risk factor in some of the studies of delirium (Williams-Russo et al., 1992**;** Fisher & Flowerdew, 1995; Kolbeinsson & Jonsson, 1993; Schor et al., 1992; Edlund et al., 2001). In the meta-analysis of Elie et al., a statistically significant relative risk of 1.9 was found for the male gender (1998). In a study that investigated the differences between preoperative and postoperative delirium regarding predisposing, precipitating factors and outcome in older patients admitted to hospital with femoral neck fractures, it was found that the men with femoral neck fractures were in poorer health than the women, except that more female patients had hypertension and were treated with diuretics (Edlund et al., 2001). In the same study, male patients were reported to suffer more postoperative complications and have higher long-term mortality (Edlund et al., 2001). These factors might

Another factor contributing to the increased risk of delirium in men might be reluctance of men to consult a doctor. Men with health problems were found to be more likely than women to have had no recent contact with a doctor regardless of income or ethnicity (Courtenay, 2000). This reluctance means that men often do not seek help until a disease has

Depression has been reported to be a predisposing factor for delirium in the elderly (Elie et al., 1998) and in non-cardiac surgical patients (Dasgupta and Dumbrell, 2006). The reduced functional connectivity in the human brain which is associated with depression (Anand et al., 2005) was hypothesized to be one of the mechanisms that predispose depressive patients to delirium (Sanders, 2011). On the other hand, the authors of the data synthesis commissioned by the National Institute for Health and Clinical Excellence (NICE) reported

withdrawal and sensory/environmental causes (Brauer et al., 2000).

illness, cognitive impairment and BUN/creatinine ratio of 18 (Inouye, 1999).

**3.1.4 Severe, traumatic or systematic illnesses**

Milbrandt et al., 2004; Thomason et al., 2005).

have contributed to the increased risk of delirium in men.

**3.1.5 Male gender**

progressed (Banks, 2001).

**3.1.6 Depression**

uncertainty for depression as a precipitating factor for delirium (National Clinical Guideline Center; Steiner, 2011).