populations have increased in developing countries. nearly a billion people worldwide live in slums, and some project the figure may grow to 2 billion by 2030 if governments and the global community ignore slums and continue current urban policies. united nations habitat group believes change is possible. some ngo's are focused at addressing local problems (i.e. sanitation issues, health, ...), through the mapping out of the slums and its health services, creation of latrines, creation of local food production projects, and even microcredit projects. in one project (in rio de janeiro), the government even employed slum residents for the reforestation of a nearby location. to achieve the goal of "cities without slums", the un claims that governments must undertake vigorous urban planning, city management, infrastructure development, slum upgrading and poverty reduction. slum removal a slum dwelling in borgergade in central copenhagen denmark, about 1940. the danish government passed the slum clearance act in 1939, demolished many slums including borgergade, replacing it with modern buildings by the early 1950s. some city and state officials have simply sought to remove slums. this strategy for dealing with slums is rooted in the fact that slums typically start illegally on someone else's land property, and they are not recognized by the state. as the slum started by violating another's property rights, the residents have no legal claim to the land. critics argue that slum removal by force tend to ignore the social problems that cause slums. the poor children as well as working adults of a city's informal economy need a place to live. slum clearance removes the slum, but it does not remove the causes that create and maintain the slum. slum relocation slum relocation strategies rely on removing the slums and relocating the slum poor to free semi-rural peripheries of cities, sometimes in free housing. this strategy ignores several dimensions of a slum life. the strategy sees slum as merely a place where the poor lives. in reality, slums are often integrated with every aspect of a slum resident's life, including sources of employment, distance from work, and social life. slum relocation that displaces the poor from opportunities to earn a livelihood, generates economic insecurity in the poor. in some cases, the slum residents oppose relocation even if the replacement land and housing to the outskirts of cities is of better quality than their current house. examples include zone one tondo organization of manila, philippines, and abahlali basemjondolo of durban, south africa. in other cases, such as ennakhil slum relocation project in morocco, systematic social mediation has worked. the slum residents have been convinced that their current location is a health hazard, prone to natural disaster, or that the alternative location is well connected to employment opportunities. slum upgrading some governments have begun to approach slums as a possible opportunity to urban development by slum upgrading. this approach was inspired in part by the theoretical writings of john turner in 1972. the approach seeks to upgrade the slum with basic infrastructure such as sanitation, safe drinking water, safe electricity distribution, paved roads, rain water drainage system, and bus/metro stops. the assumption behind this approach is that if slums are given basic services and tenure security – that is, the slum will not be destroyed and slum residents will not be evicted, then the residents will rebuild their own housing, engage their slum community to live better, and over time attract investment from government organizations and businesses. turner argued not to demolish the housing, but to improve the environment: if governments can clear existing slums of unsanitary human waste, polluted water and litter, and from muddy unlit lanes, they do not have to worry about the shanty housing. "squatters" have shown great organizational skills in terms of land management, and they will maintain the infrastructure that is provided. in mexico city for example, the government attempted to upgrade and urbanize settled slums in the periphery during the 1970s and 1980s by including basic amenities such as concrete roads, parks, illumination and sewage. currently, most slums in mexico city face basic characteristics of traditional slums, characterized to some extent in housing, population density, crime and poverty, however, the vast majority of its inhabitants have access to basic amenities and most areas are connected to major roads and completely urbanized. nevertheless, smaller settlements lacking these can still be found in the periphery of the city and its inhabitants are known as "paracaidistas". a more recent example of slum-upgrading approach is primed initiative in medellin, colombia, where streets, metrocable transportation and other public infrastructure has been added. these slum infrastructure upgrades were combined with city infrastructure upgrade such as addition of metro, paved roads and highways to empower all city residents including the poor with reliable access throughout city. most slum upgrading projects, however, have produced mixed results. while initial evaluations were promising and success stories widely reported by media, evaluations done 5 to 10 years after a project completion have been disappointing. herbert werlin notes that the initial benefits of slum upgrading efforts have been ephemeral. the slum upgrading projects in kampungs of jakarta, indonesia, for example, looked promising in first few years after upgrade, but thereafter returned to a condition worse than before, particularly in terms of sanitation, environmental problems and safety of drinking water. communal toilets provided under slum upgrading effort were poorly maintained, and abandoned by slum residents of jakarta. similarly slum upgrading efforts in philippines, india and brazil have proven to be excessively more expensive than initially estimated, and the condition of the slums 10 years after completion of slum upgrading has been slum like. the anticipated benefits of slum upgrading, claims werlin, have proven to be a myth. there is limited but consistent evidence that slums upgrading may prevent diarrhoeal diseases and water-related expenditure. slum upgrading is largely a government controlled, funded and run process, rather than a competitive market driven process. krueckeberg and paulsen note conflicting politics, government corruption and street violence in slum regularization process is part of the reality. slum upgrading and tenure regularization also upgrade and regularize the slum bosses and political agendas, while threatening the influence and power of municipal officials and ministries. slum upgrading does not address poverty, low paying jobs from informal economy, and other characteristics of slums. recent research shows that the lack of these options make residents to undertake measures to assure their working needs. one example in the northeast of brazil, vila s. pedro, was mischaracterized by informal self-constructions by residents to restore working opportunities originally employed in the informal settlement. it is unclear whether slum upgrading can lead to long-term sustainable improvement to slums. urban infrastructure development and public housing housing projects in chalco, mexico housing projects in bahia, brazil urban infrastructure such as reliable high speed mass transit system, motorways/interstates, and public housing projects have been cited as responsible for the disappearance of major slums in the united states and europe from the 1960s through 1970s. charles pearson argued in uk parliament that mass transit would enable london to reduce slums and relocate slum dwellers. his proposal was initially rejected for lack of land and other reasons; but pearson and others persisted with creative proposals such as building the mass transit under the major roads already in use and owned by the city. london underground was born, and its expansion has been credited to reducing slums in respective cities (and to an extent, the new york city subway's smaller expansion). as cities expanded and business parks scattered due to cost ineffectiveness, people moved to live in the suburbs; thus retail, logistics, house maintenance and other businesses followed demand patterns. city governments used infrastructure investments and urban planning to distribute work, housing, green areas, retail, schools and population densities. affordable public mass transit in cities such as new york city, london and paris allowed the poor to reach areas where they could earn a livelihood. public and council housing projects cleared slums and provided more sanitary housing options than what existed before the 1950s. slum clearance became a priority policy in europe between 1950–1970s, and one of the biggest state-led programs. in the uk, the slum clearance effort was bigger in scale than the formation of british railways, the national health service and other state programs. uk government data suggests the clearances that took place after 1955 demolished about 1.5 million slum properties, resettling about 15% of uk's population out of these properties. similarly, after 1950, denmark and others pursued parallel initiatives to clear slums and resettle the slum residents. the us and european governments additionally created a procedure by which the poor could directly apply to the government for housing assistance, thus becoming a partner to identifying and meeting the housing needs of its citizens. one historically effective approach to reduce and prevent slums has been citywide infrastructure development combined with affordable, reliable public mass transport and public housing projects. however, slum relocation in the name of urban development is criticized for uprooting communities without consultation or consideration of ongoing livelihood. for example, the sabarmati riverfront project, a recreational development in ahmedabad, india, forcefully relocated over 19,000 families from shacks along the river to 13 public housing complexes that were an average of 9 km away from the family's original dwelling. prevalence percent urban population of a country living in slums (un habitat, 2005) urban population living in slums, 2014. slums exist in many countries and have become a global phenomenon. a un-habitat report states that in 2006 there were nearly 1 billion people settling in slum settlements in most cities of central america, asia, south america and africa, and a smaller number in the cities of europe and north america. in 2012, according to un-habitat, about 863 million people in the developing world lived in slums. of these, the urban slum population at mid-year was around 213 million in sub-saharan africa, 207 million in east asia, 201 million in south asia, 113 million in latin america and caribbean, 80 million in southeast asia, 36 million in west asia, and 13 million in north africa.: 127 among individual countries, the proportion of urban residents living in slum areas in 2009 was highest in the central african republic (95.9%), chad (89.3%), niger (81.7%), and mozambique (80.5%). the distribution of slums within a city varies throughout the world. in most of the developed countries, it is easier to distinguish the slum-areas and non-slum areas. in the united states, slum dwellers are usually in city neighborhoods and inner suburbs, while in europe, they are more common in high rise housing on the urban outskirts. in many developing countries, slums are prevalent as distributed pockets or as urban orbits of densely constructed informal settlements. in some cities, especially in countries in south asia and sub-saharan africa, slums are not just marginalized neighborhoods holding a small population; slums are widespread, and are home to a large part of urban population. these are sometimes called slum cities. the percentage of developing world's urban population living in slums has been dropping with economic development, even while total urban population has been increasing. in 1990, 46 percent of the urban population lived in slums; by 2000, the percentage had dropped to 39%; which further dropped to 32% by 2010.