Urbanization Impacts and Issues

What is Urbanization?

Urbanization is an increase in the number of people living in centralized cities and towns, typically accompanied by a flattening or decrease in the number of people living in rural areas. Although humans have congregated in urban centers since the earliest civilizations, the share of the world's population living in urban areas did not exceed that of those living in rural areas until 2008. By 2050 some 70 percent of the world's population is expected to live in cities, due in large part to rapid urbanization among developing countries.

Some urbanization is caused by natural population growth, but the primary reason is large-scale migration. Rural-to-urban migration is driven by a number of push and pull factors. Push factors include high levels of poverty and unemployment in rural areas, as well as a relative lack of professional and educational opportunities and lower access to public services.

Pull factors include higher-paying jobs and access to better housing, education, health care, and infrastructure. However, many of the advantages of urban living can be lost when urbanization occurs too quickly to allow for proper planning and development of urban infrastructure.

Historical Background

The process of urbanization is as old as human civilization itself. Ancient Mesopotamian cities such as Uruk, founded around 3600 BCE, emerged as humans moved from small, family-based subsistence agriculture toward more centralized production and planning. As cities began to develop complex economies requiring specialized skills, migration from rural areas steadily increased. The population of Uruk, for example, grew 800 percent, from approximately 10,000 in 3600 BCE to as many as 80,000 in 2900 BCE.

Ancient urbanization provided several benefits to city dwellers. Food and water were, for the most part, readily available. Inhabitants faced fewer dangers from attack or exposure to the elements. Goods and information could be imported from neighboring cities. And the relative physical and economic security provided by living in large numbers allowed for other aspects of human culture, such as art, music, and religion, to flourish.

Yet, along with the growth of cities came an increasing demand for food and other natural resources that could not be produced in an urban setting. Because agricultural production prior to the 18th century was relatively unsophisticated, demand for rural labor remained high. Even in thriving civilizations such as ancient Rome, approximately two-thirds of the population remained in rural areas.

Beginning in Great Britain around 1750, two simultaneous revolutions contributed to a major shift in urbanization trends. New developments in farming techniques and technologies dramatically increased crop yields, allowing much more food to be produced from the same amount of labor. Likewise, innovative manufacturing technologies led to the establishment of the factory system, and worker productivity and incomes rose sharply.

The improved quality of life afforded by the agricultural and industrial revolutions brought about a dramatic population increase in Great Britain, from fewer than 9 million at the time of the first census in 1801 to nearly 18 million at the 1851 census and more than 32 million at the 1901 census. Much of the population growth was concentrated in cities, as workers migrated from rural agricultural work to urban factory jobs. According to Paul Bairoch and Gary Goertz in a 1986 article in Urban Studies, in 1800 around 20 percent of the UK population lived in towns or cities with more than 5,000 inhabitants. By 1900, 67 percent of the population lived in urban settings. To accommodate all of the migrants entering urban areas, many landlords set up tenements, or overcrowded apartment buildings, that often lacked access to appropriate sanitation.

As the agricultural and industrial revolutions gradually spread throughout Western Europe and North America, similar trends toward urbanization began to take hold. In 1800 only around 3 percent of the world lived in cities. By 1900 approximately 15 percent of the global population were urban dwellers, and by 1950 over 30 percent of the world population lived in cities. But strong disparities existed between wealthy and poor countries. In 1950, according to the United Nations (UN) Population Division, the most developed countries were around 55 percent urban, while about 18 percent of the population in less developed countries were urban dwellers, and the least developed countries had 7.5 percent.


A type of economy that benefits from concentrating businesses, services, and industries near each other.
The act of declaring independence from colonial powers and asserting national sovereignty.
The increasing integration of the global economy through such practices as free trade and the establishment of multinational corporations.
The monetary value of all goods and services produced by citizens of that country, regardless of whether the citizen is living within the country's borders.
The value of goods and services produced by a national economy divided by the population of the country.
According to the push-pull theory of migration, something that attracts a migrant to a new place of residence.
According to the push-pull theory of migration, something that drives a migrant away from his or her place of residence.
Heavily populated, urban areas characterized by low-quality housing and a lack of civic amenities. People living in slums are generally poor.
Farming done to provide food for farmers and their families rather than for sale to others.
Goals that promote economic growth while also preserving natural resources for future generations.

In the second half of the 20th century, however, political and economic trends such as globalization, decolonization, and a shift among developed countries away from manufacturing toward a service-based economy (in which most industries involve providing services for others, such as health care, education, hospitality, retail, or banking) brought increased urbanization to developing countries. This was especially true in upper-middle-income countries with robust industrial sectors, such as China and Brazil, which saw their urban populations grow from 20 percent of the total in 1950 to over 50 percent in 2000 and more than 60 percent in 2015, according to a 2014 report from the UN Population Division. High-income countries had the largest urban populations but saw slower rates of growth, going from 55 percent in 1950 to 80 percent in 2014. The lowest rates of urban growth were in lowincome countries, which rose from 9 percent in 1950 to around 30 percent in 2015. In especially poor countries in sub-Saharan Africa, eastern Asia, and the Caribbean, as little as 10 to 20 percent of the population lived in cities as of 2015.

Projections by the UN and others, however, suggest that the developing world will be at the center of a massive increase in urban populations in the coming decades. Overall, in 2014 the world's urban population stood at 3.9 billion, compared to 3.3 billion living in rural areas. By 2050 the urban population is expected to grow to 6.3 billion, while the rural population is projected to decline to around 3.2 billion. As much as 90 percent of the urban population increase is predicted in developing countries, which will experience an urban population growth of more than 2 billion, from around 3 billion to 5.2 billion, while urban populations in developed countries will increase slightly, from 986 million to 1.1 billion.

Impacts and Issues

One significant reason for the ongoing rapid increase in urban populations among developing countries is the expectation that urbanization will coincide with economic development. In 2016, according to the UN, approximately 80 percent of global gross domestic product (GDP) was generated in the world's cities. Agglomeration economies that result from urbanization and industrialization have numerous advantages, including better access to consumers, resources, skilled labor, and transportation networks. Thus, many governments expect that an increase in urban populations will coincide with a proportionate increase in economic production, leading to rising incomes and lower rates of poverty.

Historically, the link between urbanization and economic growth has been strong. The rapid development of countries in Western Europe and North America in the 19th and 20th centuries is an obvious example of this correlation. This trend played out in some countries in the developing world in the second half of the 20th century. For example, China's urban population grew from less than 20 percent of the total in 1980 to more than 55 percent in 2015, and its per capita GDP increased from $299 to $14,388 over the same period, according to figures published by the Organisation for Economic Co-operation and Development (OECD). This corresponded with a decrease in the rate of extreme poverty, from 84 percent to less than 10 percent, according to the UN.

Yet, in the 21st century the relationship between urbanization and development has become less clear. Whereas China's urbanization was accompanied by a corresponding industrialization, which created better-paying jobs and made the country a major player in the global economy, many countries have experienced a similar growth in urban populations without the same increase in industrial output. This phenomenon is particularly observable in countries in sub-Saharan Africa, where natural resources (oil, minerals, and cash crops) remain the primary sources of income.

The revenues from these industries supported improvements in power and transportation infrastructure, health care, and education services in major cities, which created a strong pull factor that contributed to a doubling of the urban population between 1995 and 2015. But a lack of industrialization, variations in global commodity prices, and high overall population growth meant that per capita GDP in the region has remained largely flat.


The world is becoming increasingly urbanized, but cities themselves are becoming less dense. That is, the number of people living in a given unit of urban land area has decreased. In the United States, for example, the 2010 census showed a 6-percent decline in population densities in metropolitan areas between 2000 and 2010. In Shanghai, China, the population density fell by as much as 20 percent over the same period. As the United Nations Human Settlements Programme's World Cities Report 2016 states, “built-up area densities have been on a decline around the world, especially in developing countries.”

Rising urban populations and falling urban population densities mean that cities and their residents are becoming more spread out, a process known as suburbanization. The movement of large numbers of urban dwellers away from crowded city centers has a long history in the United States, beginning in the 1920s as factories began to appear on the outskirts of cities. Workers soon followed, and in the 1950s post–World War II prosperity, as well as racial tensions between white city-dwellers and the growing number of African American migrants from rural areas in the South, contributed to a massive wave of suburbanization.

The city of Detroit, for example, lost nearly 1 million residents between 1950 and 2000, while the surrounding metropolitan area gained well over 3 million. In many cases immigrants kept once-thriving inner cities from financial peril by replacing part of the tax revenues lost from the exodus of middle-class workers. A similar pattern emerged in Western Europe in the 1950s but was less pronounced due to more stringent land use regulations and urban boundary laws. In the 21st century the pattern has largely been repeated throughout the developing world.

One reason for the ongoing trend suggested by researchers is that, as wealth increases in a city, so does the rate of suburbanization. The emergence of China as a major economic power in the late 20th century, for example, coincided with growing rates of suburbanization. Forbes magazine notes that the world's densest megacity, Dhaka, Bangladesh, which had approximately 115,000 residents per square mile in 2013, also had the lowest per capita gross domestic product (GDP) of all 28 megacities in the world, at $3,100. The two least dense megacities, New York (4,600 per square mile) and Los Angeles (6,300 per square mile), had the first-and third-highest per capita GDPs at $63,100 and $54,400, respectively.

Rising urban wealth is commonly associated with the development of what has been called the “hourglass economy,” in which there is a sharp divide between high-skill, high-paying jobs and low-skill, low-paying jobs, with little middle ground between the rich and the poor. High-paying service-sector jobs are increasingly locating in city centers, pushing low-skilled workers toward the suburbs, which have seen much higher rates of poverty throughout the developed world. Similarly, in the developing world most slums are located not in the inner city but on the edges of town.

Researchers caution against the popular assumption that suburbs are experiencing a decline similar to that experienced by major cities in the second half of the 20th century. Instead, they suggest that suburbs are simply becoming more economically diverse, no longer home to a select group of relatively wealthy middle-class workers. To accurately prepare for the urbanization boom of the 21st century, they argue, urban planners and government officials must give as much consideration to suburban areas as urban cores.

Negative Effects of Urbanization

When cities experience a rapid influx of migrants from rural areas without a concurrent increase in economic development, they are at risk of several significant and related challenges, including increased poverty, overcrowding, wealth inequality, and environmental degradation. Most of the problems can be traced to a lack of affordable housing, which occurs when demand for housing increases without new structures being built, driving up prices. Rural migrants drawn to the city by the promise of new opportunities or pushed from rural areas by threat of famine or violence often do not have the skills or resources to assimilate into the local economy and struggle to survive on the fringes of society.

In 2013 approximately 62 percent of urban residents in sub-Saharan Africa lived in slums, according to the International Organization for Migration. Likewise, 35 percent of India's urban population lived in slums, as did 31 percent of the urban population in Southeast Asia and 24 percent in Latin America and Oceania. Slums are subject to significantly higher levels of disease and crime and are often disproportionately affected by natural disasters such as flooding or earthquakes. A lack of sanitary facilities and a reliance on wood for fuel can also have a severe negative impact on the surrounding natural environment.

Beyond the presence of slums, overcrowded cities face issues ranging from traffic congestion to pollution and water and energy shortages. In the face of rapidly increasing urbanization among the world's poorest countries, urban planning has become one of the most pressing issues of the 21st century. In October 2016 UN member states met in Quito, Ecuador, for the Conference on Housing and Sustainable Urban Development. There, they adopted a New Urban Agenda, a road map for governments to incorporate the UN's Sustainable Development Goals into their urban development plans and make cities more prosperous, inclusive, equal, and environmentally responsible.

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