Population, Urbanization, and the Environment


What Is Urbanization?

Urbanization is the process in which growing numbers of people move from rural to urban areas.

One of the most profound population changes that has occurred over the last 250 years is urbanization, the process in which growing numbers of people move from rural to urban areas. It is the movement of a population away from the countryside and farms and into towns and cities. Before industrialization, most people lived in rural, agricultural areas. As industrialization grew, more people moved into urban areas to take jobs in factories.

Modern cities are much larger than premodern cities. The concept of modern urban centers includes the city, the metropolis, the conurbation, and the megalopolis. A city is an urban settlement of great size, population, or importance. A metropolis is an area that includes a city and its suburbs and exurbs. The size of a metropolis can vary regionally. The population of smaller metropolitan areas (metros) can be around 50,000 inhabitants, while large metros have much larger populations, up to many millions of people. A suburb is a separate community that borders a larger city. An exurb is a type of suburb that is located even farther away from the larger metropolitan center. In the United States, many suburbs and exurbs are home to more prosperous social groups. In some countries the opposite is true. In many Western European countries, for instance, prosperous groups live in city centers, while many suburbs are considered dangerous and unattractive. Conurbations and a megalopolises are similar concepts. A conurbation is a chain of cities and towns that have expanded into one another to form a continuous urban region. A megalopolis is a supercity. It is a large conurbation where cities have expanded outward to meet, forming an urban center larger than a metropolis.

In the 1920s scholars at the University of Chicago began studying urban sociology. Known as the "Chicago School," these scholars developed new approaches to understanding connections between urban life and social behavior. One key concept that came out of the Chicago School is urban ecology, the study of the relationship people living in cities have with one another and their urban environment. It explores urban ecosystems, analyzing the roles and interactions of humans and other species. In the urban ecology model, cities develop according to natural, predictable patterns. According to this model, cities are arranged in concentric circles radiating from the city center. The inner circles have higher concentrations of poverty, overcrowding, and crime. Crime, poverty, and overcrowding decline as the circles expand outward. The outermost circles are more affluent areas with both wider spacing between housing and lower crime rates.

The concept of urban ecology has been influential in the field of urban sociology. But researchers have questioned whether these patterns are natural, as the Chicago School theorized, or socially constructed. A large 1945 study concluded that in the United States, social forces kept minority populations inside the most inner circles. These groups had no choice. Social and structural forces excluded them from more favorable living conditions and opportunities. For example, the federal G.I. Bill gave home loans primarily to white families but not to black families. Nonwhite families could only access housing in economically depressed areas. Other sociologists assert that influential segments of society, including politicians and developers, create city spaces that benefit middle and upper classes at the expense of lower classes. This can be seen in some extremely expensive major urban centers, such as Manhattan (the central part of New York City) and many European cities, including Paris, London, Dublin, and Amsterdam.

Effects of Urbanization

Effects related to urbanization include increased urban density, sprawl, and gentrification.

Louis Wirth, a sociologist of the Chicago School, developed the concept of urbanism as a way of life. Wirth noted several differences between urban and rural life. The differences are a result of urban density, or the number of people inhabiting a given urbanized area. There are simply more people living in cities than in rural areas. Wirth noted that when so many people live in such close proximity, they develop habits that disengage them from strangers. They may seem apathetic toward others. However, other sociologists have pointed out that so many people in such close proximity means urban dwellers are able to find people who share their interests. They develop subcultures and neighborhoods that have their own distinct characteristics.

Another result of urban density is increased tolerance and acceptance of other cultures. One explanation of why urban density can lead to more cross-cultural acceptance is contact hypothesis, the theory that contact between two groups can promote tolerance and acceptance. Urban residents come into contact with a variety of different cultures, attitudes, and lifestyles. Because of this, they are less likely to believe negative stereotypes about other cultures. They are more open to and accepting of people different from them than rural residents are. However, other researchers point to the ways that more contact between different groups and cultures can lead to more conflict. Some urban areas have high levels of conflict between different racial, ethnic, and religious groups, who are forced to interact with one another against their wishes and preferences.

Cities are filled with diversity and cultural attractions, such as museums, theaters, and restaurants. But cities are also filled with less attractive components, including poverty, overcrowding, substandard housing, crime, traffic, and pollution. As cities have become more crowded, many people seek to migrate out of them. They tend not to migrate back to rural areas. They want to stay close to their jobs and other amenities of city life. Instead, people move to the outer edges of the city and to suburbs. This contributes to urban sprawl, also called sprawl––the spread of urban developments, such as housing and retail centers, to undeveloped land surrounding a city. Urban sprawl leads to increased traffic and pollution as people from outer areas commute to jobs in the city.

An opposite trend is gentrification, the renovation of deteriorated urban neighborhoods by more affluent people moving into the area. Middle- and upper-class people move into historically poor urban areas and upgrade the housing and other buildings. Gentrification is controversial. On the one hand, it improves the quality of an area, increases its value, and reduces its poverty, overcrowding, and crime. On the other hand, gentrification pushes the current poorer residents out of the neighborhood and into even less desirable areas of the city. This is known as displacement—the experience of being pushed out of an area and into a different area.

Potential Impacts of Gentrification
Positive Impacts Negative Impacts
Improvements to property Loss of affordable housing
Increased property values Community resentment
Reduced vacancy rates Increased homelessness
Stabilization of declining area Displacement of businesses
Increase in stores and other businesses, creating increased employment opportunities Displacement of residents because of increased rent and property taxes
Increased social mix, with more racial, ethnic, economic, and other types of diversity Decreased social mix, with less racial, ethnic, economic, and other types of diversity
Reduction in crime Conflict between longtime residents and new residents


Suburbanization is a post–World War II phenomenon that represents a newer form of income and racial segregation.

Suburbanization is a population shift from central urban areas into suburbs. It is the development and inhabitation of residential communities on the outskirts of a city. Causes of suburbanization include both push factors and pull factors. Push factors are circumstances that encourage people to move out of urban areas, such as high housing prices, poor schools, or high crime rates. Pull factors are characteristics that encourage people to move to suburbs, such as the possibility to live in a larger home, less traffic, or highly ranked schools. In the United States, many suburbs are autonomous municipalities. That is, they are incorporated towns and cities of their own, separate from the government and administration of the larger city they surround. Suburbanization is a chief contributor to urban sprawl.

Wide-scale suburbanization in the United States began after World War II. The postwar economy was booming. Soldiers coming back from the war wanted to realize the American dream of raising their families in homes they owned. In addition a shortage of housing in cities led to skyrocketing rent. The Federal Housing Administration (FHA) began offering low-cost loans on new homes in the suburbs. Mortgages for suburban homes became cheaper than rent in the city. In 1956 Congress passed the Federal-Aid Highway Act, funding construction for the interstate highway system. At the same time, automobile manufacturing increased. Commuting from the suburbs became easier than ever before.

In this flurry of suburbanization, it was almost exclusively white people who were suburbanizing. The massive migrations of white people to the suburbs is sometimes called white flight. It is one example of self-segregation, or the separation of a group from the rest of society by the group itself. Some groups self-segregate to keep their culture intact, such as when members of an ethnic group live and open businesses in a particular neighborhood. Other groups self-segregate from others they consider inferior. The suburbanization of the mid-20th century in the United States was due in part to this kind of self-segregation. It represented a new kind of racial segregation at a time when legally enforced racial segregation was being struck down by courts. Another factor in suburbanization and racial segregation in the United States is the discriminatory practices used by the federal government after World War II. The Federal Housing Authority (FHA) systematically provided loans to white families while denying them to people of color. A severe housing shortage followed World War II. FHA loans allowed and encouraged many white families to move to new homes in the suburbs, while people of color did not benefit from this opportunity.

Suburbanization also led to greater income segregation. As white families moved to the suburbs, housing prices in cities fell. Black and other minority homeowners in cities found that their property values had decreased. Businesses and industrial centers, too, began moving to the suburbs, resulting in fewer jobs for people still living in cities. As suburbs flourished, cities decayed.

In the 1980s more people from minority populations, including African Americans, Hispanics, and Asian Americans, began moving to the suburbs. At the same time, white migration to exurbs also increased. Some researchers explain this using the framework of group threat theory, the idea that when minority groups grow in size or power, the majority group feels threatened.