There are a lot of different ways to measure the relative "greenness" of a given city. 
 
 You can look the energy efficiency of its buildings, the average carbon footprint of its citizens or even the number or people who have "An Inconvenient Truth" in their Netflix queue. 
 
 The people behind event finding app Gravy, on the other hand, used a different measure in determining their list of the greenest cities in America--the number of "green-friendly" events happening in a given year. 
 
 Does a critical mass of self-congratulatory "awareness building" festivals necessarily translate into a city and its citizens making serious strides toward protecting the Earth? 
 
 Of course not. But looking at the overall number of events does yield a pretty good idea of a city's level of publicly stated commitment to environmentalism, which often results in action. So it's not exactly surprising that the cities sitting atop Gravy's list for hosting the most environmentally-themed events also tend to cluster near the top of rankings of greenest cities based on other metrics. 
 
 Check out this list of Gravy's five "Most Earth-Friendly Cities" that comes complete with a unique Earth Day activity for each city: 
 
 Most Earth-Friendly Cities ||||| Which cities show the most eco-friendly pride? In honor of Earth Day, T+L readers separate the composters from the posers to determine America’s greenest cities. 
 
 San Francisco has a nationwide reputation for sustainable dining, but that’s not enough for many of its restaurants, which go to extra lengths to demonstrate their green practices. 
 
 “I’ve been handed a two-page printout, detailing how a particular fish came to be on my table,” says Michael McColl, the Bay Area founder of Ecotourism-Newswire.com. 
 
 Such attention to detail helps explain how San Francisco secured its spot among the top 10 of America’s Greenest Cities, according to the Travel + Leisure community. As part of the annual America’s Favorite Cities survey, readers ranked 35 metropolitan areas on a variety of travel-friendly qualities, from hotels to local microbrews and good wireless coverage. 
 
 To determine the greenest cities, we tallied the results from three survey categories: cleanliness, pedestrian-friendliness and public transit, and great public parks, which offset that urban asphalt and improve air quality. The high-ranking cities support other green initiatives that benefit travelers as well as locals: in Denver, the Brown Palace Hotel uses water from its own artesian well. Minneapolis offers cheap, easy-access bike rentals. 
 
 Then there’s Portland, OR, rated America’s No. 1 greenest city, where every day feels like Earth Day. One fourth of the city is shaded by tree canopy, and the ground itself features 288 parks. The Heathman Hotel, near light-rail and streetcar stops, completed a green overhaul and now even recycles “gently used” soap and shampoos, having them treated before sending them to area shelters. 
 
 Other American cities, of course, are eco-friendly in ways that aren’t always readily obvious. In a Siemens 2011 study that measured CO2 emissions, land use, air quality, and environmental governance, San Francisco came out on top—the city currently recycles 78 percent of its waste—and New York City ranked in the top 3 for its efficient land use and mass transit. 
 
 The Big Apple, however, didn’t crack the top 20 with Travel + Leisure voters, who were perhaps distracted by a rude welcome or subway stations in need of a good scrubbing. To be fair, the survey is based on readers’ perceptions, which can be skewed, and may not take into account recent improvements like New York’s expanding bike lanes and the High Line, a former rail track converted into an extraordinary park. 
 
 So which did make the green grade with T+L’s community? Read on for America’s greenest cities—and share your opinions in the comments below. ||||| The first Earth Day, on April 22, 1970, was a milestone event for the planet. An estimated 20 million people took to the streets across the U.S. to raise awareness about the impacts of human activities on the environment. 
 
 Since then, the annual tradition has grown to involve billions of people around the world. This year, Earth Day turns 48. To mark this anniversary and to show how much has changed since 1970, we assembled 48 of the most significant accomplishments of the environmental movement since the first Earth Day. 
 
 1. 1970 "Environmental Magna Carta" 
 
 The National Environmental Policy Act of 1969 went into effect the following year, becoming a landmark law that requires every major decision of the federal government to be evaluated for its impact on the environment. This began the era of requiring environmental impact statements for building dams, roads, and other major projects. It has been called the "environmental Magna Carta" for its wide impact and for the precedent it set in government, both in the U.S. and abroad. 
 
 2. 1972 Notorious Toxic Chemical Banned 
 
 DDT (dichlorodiphenyltrichloroethane) is a colorless, nearly odorless insecticide that was widely used in the post-war era to increase farm productivity and fight mosquitoes. Although a Nobel Prize was awarded for its discovery, scientists eventually realized that DDT was causing problems in the environment, including thinning the shells of birds' eggs. Rachel Carson popularized this research in the 1962 book Silent Spring. After DDT was banned, bald eagles, peregrine falcons and many other endangered bird species returned from the brink of extinction. 
 
 3. 1972 Regulating Pesticides 
 
 In 1972, the Federal Environmental Pesticide Control Act was passed, updating a 1910 law that had required truth in advertising for pesticides. The new law charged regulators with considering the impacts of pesticides on human and environmental health, which at the time was a relatively new concept. The Environmental Protection Agency was given more teeth to police the market and restrict and outlaw toxic chemicals. 
 
 4. 1972 Cleaning Up Rivers 
 
 In 1972, the Clean Water Act passed, with the goal of making all rivers in the country swimmable and fishable again. In just a few years, the resulting efforts to restrict pollution led to rivers that no longer burst into flames. 
 
 5. 1972 Marine Sanctuaries Created 
 
 Although governments had been protecting land as wilderness areas for more than a century, the idea took longer to catch on for the ocean. In 1972, the Marine Protection, Research and Sanctuaries Act started the country's system of marine sanctuaries. These special places now protect priceless biological, historical, and cultural treasures, from the reefs of the Florida Keys to shipwrecks in the Great Lakes. The sanctuaries also become a boon to the tourism industry. 
 
 6. 1972 Saving Whales 
 
 Whales, dolphins, seals, and manatees received strict protection from hunting and harassment in U.S. waters with the Marine Mammal Protection Act. As a result, their numbers began to slowly recover in the ensuing decades. A robust eco-tourism business followed in their wake. 
 
 7. 1973 Saving Species 
 
 The landmark Endangered Species Act resulted in substantial protections for listed plants and animals, including bans on harvesting and a framework that protects critical habitat. In some cases, captive breeding and reintroduction programs began in an effort to reverse decades of population declines caused by human activities. Species that showed significant recovery as a result range from the toothy American crocodile to the plucky Delmarva fox squirrel. 
 
 8. 1975 Global Agreement on Endangered Species 
 
 The Convention on International Trade in Endangered Species was drafted for signatures in 1973 and went into effect in 1975. Signatory countries agree to ban or restrict trade in endangered species and their body parts. Although black markets arose for such products as tiger skins and elephant tusks, countries have also worked together to combat such trafficking. 
 
 9. 1974 Safe(r) Drinking Water 
 
 View Images Thanks to conservation efforts, bald eagles were removed from the Endangered Species List in 1995. Photograph by Klaus Nigge, Nat Geo Image Collection 
 
 In response to rising concerns and scientific awareness about the impacts of pollution on health, the Safe Drinking Water Act set quality standards for all U.S. drinking water systems. 
 
 10. 1974 Getting the Lead Out of Gas 
 
 In 1974, the EPA began a phaseout of lead from gasoline in the U.S., a process that completed in 1995. The toxic element was originally added to boost engine performance, but scientists eventually discovered that it was building up in soils and becoming a serious air pollutant. The EPA estimated more than 5,000 Americans died per year from heart disease linked to lead poisoning. Since the ban, the average level of lead in the blood of Americans has decreased by more than 75%. 
 
 11. 1976 Chemical Control 
 
 The Toxic Substances Control Act oversees the introduction of new chemicals into the marketplace. Those substances that are found to pose a significant risk to human health or the environment may be restricted or banned. A notable example was the banning of PCBs (polychlorinated biphenyls) after 1978. The chemicals were widely used in industrial applications but were found to cause cancer. 
 
 12. 1978 Love Canal Causes National Outcry 
 
 After hundreds of residents of the Love Canal planned community in Niagara Falls, New York, were sickened by leaking toxic waste, a spotlight was shined on the dangers of industrial pollution. Local parent Lois Gibbs organized the community after her son took ill, starting a model for grassroots environmental activism. The neighborhood was eventually demolished and cleaned. 
 
 13. 1980 Superfund Program Launched 
 
 Outrage over Love Canal helped lead to the passage of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980, commonly known as Superfund. The goal of the law is cleaning up toxic sites, and the Environmental Protection Agency can try to recover the costs of doing so from the polluters. Love Canal became one of hundreds of sites cleaned up by the program, though many more locations are still awaiting treatment. 
 
 14. 1980 Vast Alaskan Lands Protected 
 
 Congress passed and Jimmy Carter signed the Alaska National Interest Lands Conservation Act in late 1980, creating a massive series of national parks, reserves, and refuges that protected more than a hundred million acres of wilderness for future generations. Highlights include the national parks Wrangell-St. Elias, Glacier Bay, and Gates of the Arctic. 
 
 15. 1982 Saving More Whales 
 
 In 1982, the International Whaling Commission finally adopted a moratorium on commercial whaling around the world, in response to more than a decade of protests and pressure from scientists. Although pirate and controversial "scientific" whale hunts continued, the end of large-scale whaling marked a big turning point for the animals, and most species began a slow recovery from the brink of extinction. 
 
 16. 1986 McPackaging Improves 
 
 In 1986, McDonalds started using biodegradable packaging, in response to criticism from environmentalists over mountains of Styrofoam containers littering roadways and choking landfills. Campaigners declared a major win, and the effort helped usher in a new era of companies both working with advocacy groups and acting on their own to reduce their environmental impact. The effort also helped raise consumer awareness about the impact of their own daily choices. 
 
 17. 1986 A Civil Action 
 
 In 1986, the sprawling Woburn, Massachusetts pollution case was decided in court. Although the result was mixed for the families that sued polluters over injury to their children, the high-profile case set a big precedent in environmental law and in the court of public opinion. The case was depicted in the 1995 book (and later movie) A Civil Action. 
 
 18. 1987 Saving Condors 
 
 In 1987, wildlife biologists made the tough decision to bring all 27 remaining California condors into captivity. They launched a breeding program, which was almost derailed by a tragic fire. But eventually, scientists were able to successfully reintroduce some of the offspring. Combined with efforts to protect the birds in their native habitat, the result has been a slow recovery of the species, which now numbers over 400. 
 
 19. 1987 Plugging the Ozone Hole 
 
 In 1987, many of the world's nations came together to agree on the Montreal Protocol, which outlawed a series of chemicals that had been destroying the Earth's protective ozone layer. Most famous among these were chlorofluorocarbons. Scientists were concerned that the loss of the ozone layer could lead to blistering rates of skin cancer and other problems. The ozone hole is now healing. 
 
 20. 1987 Cleaning Up Sewage 
 
 View Images Presidents George W. Bush and Barack Obama both took steps to preserve ocean waters. See fact 40 for more information. Photograph by Brian Skerry, Nat Geo Image Collection 
 
 Once industrial pollution was reigned in, regulators turned to another major source of water quality problems: sewage waste. The Water Quality Act of 1987 created the Clean Water State Revolving Fund, which helped finance the upgrade of water systems across the country. 
 
 21. 1988 Cleaning Up Medical Waste 
 
 In the late 1980s, the public was shocked after waves of medical waste washed up on beaches where children played. The response was the 1988 Medical Waste Tracking Act, which compelled healthcare providers to treat their waste seriously and make sure it gets disposed of properly. 
 
 22. 1989 Get the Asbestos Out 
 
 In 1989 the U.S. began a phaseout of asbestos from many products, after evidence mounted that it could cause a rare form of lung cancer. Asbestos was previously considered a new wonder material thanks to its light weight and resistance to fire. 
 
 23. 1990 Clearing the Air 
 
 Although the Clean Air Act was originally passed in 1963, it received a major update in 1990, which targeted acid rain and ozone depletion. The law also established a tougher permitting and oversight system for polluters and required cleaner gasoline. 
 
 24. 1992 Rio Earth Summit 
 
 The United Nations Conference on Environment and Development was a major event in Rio de Janeiro that helped focus the world's attention on big environmental problems. It spurred all kinds of solutions, from government to civil society and business. It was there that countries agreed to start working together to address climate change. Countries also committed to increasing their use of renewable energy and to respecting the needs of indigenous people, efforts that were amplified when the UN met again in Rio 20 years later. 
 
 25. 1991 Saving Ferrets 
 
 In 1991, U.S. Fish and Wildlife Service scientists began reintroducing black-footed ferrets to the American West. The species was declared extinct in 1979, but a few dozen individuals were later found and entered into a captive breeding program. Now, there are an estimated 1,000 of the animals in several populations in the wild. 
 
 26. 1993 Erin Brockovich Wins Her Case 
 
 Later immortalized in film, determined law clerk Erin Brokovich and her firm Masry & Vititoe scored a $333 million win against a California utility accused of poisoning people's groundwater with a toxic chemical. It was the largest settlement ever paid in a direct-action lawsuit. 
 
 27. 1993 Green Building Takes Off 
 
 In 1993, the U.S. Green Building Council was founded, helping kick off a revolution in environmentally friendly design that continues to grow each year. Architects and manufacturers have made big gains in energy efficiency, renewable energy, and sustainable materials. 
 
 28. 1993 Protecting Biodiversity 
 
 In 1993, the Convention on Biological Diversity went into effect after being ratified by enough countries. Nations pledged to work to protect biodiversity around the world, in a decision that is often seen as the foundation for sustainable development. 
 
 29. 1995 Gray Wolves Reintroduced to Yellowstone 
 
 After generations of absence, wolves were returned to an iconic national park. They quickly regained their past position in the web of life, restoring balance to prey species and even changing the course of rivers. Today Yellowstone remains a critical preserve as well as living laboratory for ecology. 
 
 30. 1995 Bald Eagle Recovery 
 
 In 1995 bald eagles were removed from the Endangered Species List, helping prove the power of the law. Eagles retain legal protection from hunting through other laws. 
 
 31. 1997 Early Climate Agreement 
 
 View Images Solar panels, like these in Germany, have become much more common around the world in recent decades. Photograph by Luca Locatelli, National Geographic 
 
 In 1997 the Kyoto Protocol was adopted by some countries (although not the U.S). It marked an early serious attempt by world leaders to address global warming in a coordinated way. 
 
 32. 2000 Hybrid Revolution 
 
 Toyota first introduced the Prius in Japan in 1997, but it came to America in 2000. The high-tech car introduced the hybrid drivetrain to many consumers, helping kick off a movement toward greater fuel efficiency. Within a few years, almost every car company began offering hybrid models. 
 
 33. 2000 Green Awareness 
 
 As the old millennium ended, environmental awareness climbed toward an all-time high, spurred by decades of educational and activist campaigns. Few politicians or corporations could afford to overtly ignore the environment any longer. 
 
 34. 2001 Roadless Areas Protected 
 
 In January 2001, the U.S. Forest Service adopted the Roadless Area Conservation Rule, which protected 58.5 million acres of pristine forests and grasslands from most road construction and logging. The rule remains controversial to industry but is cheered by conservationists. 
 
 35. 2002 California Goes Solar 
 
 In 2002, California passed an aggressive Renewable Portfolio Standard in order to help stimulate the clean energy industry. After a series of adjustments, the final result is that utilities in the state must get half of their energy from renewables by 2030. Many other states passed similar standards, though the Golden State's is the most ambitious. 
 
 36. 2002 Cradle to Cradle Is Published 
 
 The book Cradle to Cradle by William McDonough and Michael Braungart helped introduce their concept of biomimetic, clean design to the public. This helped kick off a new movement to rethink all manmade processes to be more in-line with nature, including the idea of ending the concept of waste and replacing it with the idea that everything can have a use as a material for something else. 
 
 37. 2003 Electric Cars Get Cool 
 
 Tesla Motors was founded by Elon Musk in 2003, helping make electric cars cutting-edge again (after they languished in obscurity for a century). Other manufacturers also pushed forward with a new round of innovation, helping ramp up a technology that many pundits think will be a boon for the environment. 
 
 38. 2006 Al Gore's Movie 
 
 Love it or hate it, the documentary An Inconvenient Truth helped raise public awareness around the threat of climate change. 
 
 39. 2006 Sharing Fish 
 
 In 2006 the U.S. started regulating the commercial fishing industry through catch shares, in an attempt to make fishermen partners in conservation instead of adversaries. The basic idea is that each fisherman is awarded a percent share of the total catch. So the more fish that can be caught, the more each person can benefit. This helps incentivize conservation measures and accelerated the recovery of many declining U.S. fish stocks. 
 
 40. 2007 Fuel Efficiency 
 
 The Energy Independence and Security Act resulted in tougher new fuel economy standards, including the phase-in of standards for SUVs and even large commercial vehicles. Manufacturers had fought the standards for years but eventually worked with the government to meet the standards. 
 
 41. 2007 Rise of Walking 
 
 View Images Legislation, global accords, and pressure from environmentally-conscious people have all led to increases in energy efficiency and renewable energy. Photograph by Robb Kendrick, Nat Geo Image Collection 
 
 Walk Score was founded in 2007, rating cities, neighborhoods, and more for how pedestrian friendly they are. The company helped raise awareness of the growing walking and biking movements, which aim to get people out of cars and into more livable communities. 
 
 42. 2007 Big Green Apple 
 
 Mayor Michael Bloomberg issued PlaNYC in 2007, a comprehensive plan to reduce New York City's impact on the planet. It included ambitious goals to take the city toward zero waste (by promoting recycling and composting), and supported energy efficiency, tree planting, green space, biking, and much more. Many other cities around the world have issued similar plans. 
 
 43. 2009 Massive Marine Monument 
 
 In 2009, George W. Bush created the Pacific Remote Islands Marine National Monument, which protects some of the most pristine waters in the ocean. The monument was expanded by Barack Obama to nearly 490,000 square miles (1.3 million square kilometers), making it nearly three times the size of California. It protects endemic species of coral and fish, turtles, whales, and much more. 
 
 44. 2010 Protecting the Atlantic Coast 
 
 In 2010, the Department of the Interior announced a ban on oil and gas drilling in federal waters off the Atlantic Coast until 2017. This was the latest in a series of efforts to limit development off the ecologically sensitive U.S. coasts. 
 
 45. 2012 Dams Come Down 
 
 In 2012, Washington's Elwha dams were removed, restoring a wild river to Olympic National Park. This was arguably the most high profile dam removal in a growing movement that has sought to restore natural rivers and see the return of salmon runs. 
 
 46. 2015 Climate Agreement 
 
 In late 2015, nations came together in Paris and agreed to a new plan to limit global warming. The deal opens for formal signatures on Earth Day, and it will require countries to reduce emissions according to their pledges. Environmentalists are cautiously optimistic that the agreement represents a global turning point. 
 
 47. 2017 Tougher Ozone Standards 
 
 In August 2017, the Trump administration EPA dropped its decision to delay new Obama-era regulations on ozone, a long irritant that forms when sunlight irradiates emissions from vehicles, power plants, and other sources. In October 2015, the Obama administration tightened the ozone national standard from 75 parts per billion to 70 parts per billion, citing ozone’s toll on public health. The Obama administration estimated that the reduction would yield $2.9 to $5.9 billion worth of health benefits in 2025, outweighing its estimated annual cost of $1.4 billion. 
 
 48. 2018 Species Show Recovery 
 
 In April, the lesser long-nosed bat became the first bat to be taken off the Endangered Species List. After decades of conservation work, including working with agave growers to harvest tequila in a manner more friendly to the bats, the species has recovered its numbers to an estimated 200,000, up from just a few thousand. In June 2017, Yellowstone’s grizzly bears were removed from the endangered list, while the American wood stork was removed in 2014. These examples show that the Endangered Species Act is working, conservationists say. 
 
 Correction: An earlier version of this story incorrectly said the Pacific Remote Islands Marine National Monument was created in 2006; it was actually created in 2009. 
 
 Update: This story was first published on April 22, 2016 and updated on April 18, 2018.
– You can measure the green-friendliness of a city in many ways—like its average carbon footprint per citizen or the energy efficiency of buildings. But the event-finding app Gravy has decided to measure cities by the number of pro-environmental events each one hosts in a year, the Huffington Post reports. Is this an official barometer? Hardly, but it does reflect people's interest in the green movement. Here are the top five US cities, each with a unique Earth Day activity: Portland: Operation Clean Street San Francisco: Earth Day SF Boston: Earth Day Massive Spin Jam Austin: Annual Earth Day Festival Chicago: Chicago Earth Day 5K Click for more.