# Population, Urbanization, and the Environment

## Urbanization

Urbanization is the study of the social, political, and economic relationships in cities, and someone specializing in urban sociology studies those relationships. In some ways, cities can be microcosms of universal human behavior, while in others they provide a unique environment that yields its own brand of human behavior. There is no strict dividing line between rural and urban; rather, there is a continuum where one bleeds into the other. However, once a geographically concentrated population has reached approximately 100,000 people, it typically behaves like a city regardless of what its designation might be. 

### The Growth of Cities

According to sociologist Gideon Sjoberg (1965), there are three prerequisites for the development of a city: First, good environment with fresh water and a favorable climate; second, advanced technology, which will produce a food surplus to support nonfarmers; and third, strong social organization to ensure social stability and a stable economy. Most scholars agree that the first cities were developed somewhere in ancient Mesopotamia, though there are disagreements about exactly where. Most early cities were small by today’s standards, and the largest was most likely Rome, with about 650,000 inhabitants (Chandler and Fox 1974). The factors limiting the size of ancient cities included lack of adequate sewage control, limited food supply, and immigration restrictions. For example, serfs were tied to the land, and transportation was limited and inefficient. Today, the primary influence on cities’ growth is economic forces. Since the recent economic recession reduced housing prices, researchers have been waiting to see what happens to urban migration patterns in response.

### Urbanization in the United States

Urbanization in the United States proceeded rapidly during the Industrial Era. As more and more opportunities for work appeared in factories, workers left farms (and the rural communities that housed them) to move to the cities. From mill towns in Massachusetts to tenements in New York, the industrial era saw an influx of poor workers into U.S. cities. At various times throughout the country’s history, certain demographic groups, from post-Civil War southern Black people to more recent immigrants, have made their way to urban centers to seek a better life in the city. 

### Suburbs and Exurbs

As cities grew more crowded, and often more impoverished and costly, more and more people began to migrate back out of them. But instead of returning to rural small towns (like they’d resided in before moving to the city), these people needed close access to the cities for their jobs. In the 1850s, as the urban population greatly expanded and transportation options improved, suburbs developed. Suburbs are the communities surrounding cities, typically close enough for a daily commute in, but far enough away to allow for more space than city living affords. The bucolic suburban landscape of the early twentieth century has largely disappeared due to sprawl. Suburban sprawl contributes to traffic congestion, which in turn contributes to commuting time. And commuting times and distances have continued to increase as new suburbs developed farther and farther from city centers. Simultaneously, this dynamic contributed to an exponential increase in natural resource use, like petroleum, which sequentially increased pollution in the form of carbon emissions.
As the suburbs became more crowded and lost their charm, those who could afford it turned to the exurbs, communities that exist outside the ring of suburbs and are typically populated by even wealthier families who want more space and have the resources to lengthen their commute. Together, the suburbs, exurbs, and metropolitan areas all combine to form a metropolis. New York was the first U.S. megalopolis, a huge urban corridor encompassing multiple cities and their surrounding suburbs. These metropolises use vast quantities of natural resources and are a growing part of the U.S. landscape.
As the Social Policy & Debate feature illustrates, the suburbs also have their share of socio-economic problems. In the United States, White flight refers to the migration of economically secure White people from racially mixed urban areas and toward the suburbs. This occurred throughout the twentieth century, due to causes as diverse as the legal end of racial segregation established by Brown v. Board of Education to the Mariel boatlift of people fleeing Cuba for Miami. Current trends include middle-class African-American families following White flight patterns out of cities, while affluent White people return to cities that have historically had a majority of Black people. The result is that the issues of race, socio-economics, neighborhoods, and communities remain complicated and challenging.

### Urbanization around the World

During the Industrial Era, there was a growth spurt worldwide. The development of factories brought people from rural to urban areas, and new technology increased the efficiency of transportation, food production, and food preservation. For example, from the mid-1670s to the early 1900s, London's population increased from 550,000 to 7 million (Old Bailey Proceedings Online 2011). Global favorites like New York, London, and Tokyo are all examples of postindustrial cities. As cities evolve from manufacturing-based industrial to service- and information-based postindustrial societies, gentrification becomes more common. Gentrification occurs when members of the middle and upper classes enter and renovate city areas that have been historically less affluent while the poor urban underclass are forced by resulting price pressures to leave those neighborhoods for increasingly decaying portions of the city. 
Globally, 55 percent of the world’s people currently reside in urban areas, with the most urbanized region being North America (82 percent), followed by Latin America/the Caribbean (81 percent), with Europe  coming in third (74 percent). In comparison, Africa is only 40 percent urbanized, though one of its nations, Nigeria, is projected to significantly urbanize in the coming years. With 37 million people, Tokyo is the world’s largest city by population, and New Delhi is the second largest with 29 million. The world’s most densely populated cities are now largely concentrated in the global south, a marked change from several decades ago when the biggest cities were found in the global north. In the next forty years, the biggest global challenge for urbanized populations, particularly in less developed countries, will be to achieve development that occurs without depleting or damaging the natural environment, also called sustainable development (United Nations 2018).

### Theoretical Perspectives on Urbanization

The issues of urbanization play significant roles in the study of sociology. Race, economics, and human behavior intersect in cities. Let’s look at urbanization through the sociological perspectives of functionalism and conflict theory. Functional perspectives on urbanization generally focus on the ecology of the city, while conflict perspective tends to focus on political economy. 
Human ecology is a functionalist field of study that looks at the relationship between people and their built and natural physical environments (Park 1915). Generally speaking, urban land use and urban population distribution occur in a predictable pattern once we understand how people relate to their living environment. For example, in the United States, we have a transportation system geared to accommodate individuals and families in the form of interstate highways built for cars. In contrast, most parts of Europe emphasize public transportation such as high-speed rail and commuter lines, as well as walking and bicycling. The challenge for a human ecologist working in U.S. urban planning is to design landscapes and waterscapes with natural beauty, while also figuring out how to provide for free-flowing transport of innumerable vehicles, not to mention parking! 
The concentric zone model (Burgess 1925) is perhaps the most famous example of human ecology. This model views a city as a series of concentric circular areas, expanding outward from the center of the city, with various “zones” invading adjacent zones (as new categories of people and businesses overrun the edges of nearby zones) and succeeding (then after invasion, the new inhabitants repurpose the areas they have invaded and push out the previous inhabitants). In this model, Zone A, in the heart of the city, is the center of the business and cultural district. Zone B, the concentric circle surrounding the city center, is composed of formerly wealthy homes split into cheap apartments for new immigrant populations; this zone also houses small manufacturers, pawn shops, and other marginal businesses. Zone C consists of the homes of the working class and established ethnic enclaves. Zone D holds wealthy homes, white-collar workers, and shopping centers. Zone E contains the estates of the upper class (in the exurbs) and the suburbs.
In contrast to the functionalist approach, theoretical models in the conflict perspective focus on the way urban areas change according to specific decisions made by political and economic leaders. These decisions generally benefit the middle and upper classes while exploiting the working and lower classes. 
For example, sociologists Feagin and Parker (1990) suggested three factors by which political and economic leaders control urban growth. First, these leaders work alongside each other to influence urban growth and decline, determining where money flows and how land use is regulated. Second, exchange value and use value of land are balanced to favor the middle and upper classes so that, for example, public land in poor neighborhoods may be rezoned for use as industrial land. Finally, urban development is dependent on both structure (groups such as local government) and agency (individuals including businessmen and activists), and these groups engage in a push-pull dynamic that determines where and how land is actually used. For example, Not In My Back Yard (NIMBY) movements are more likely to emerge in middle and upper-class neighborhoods as engaged citizens protest poor environmental practices they fear will affect them, so these groups have more control over the use of local land.

### Summary

Cities provide numerous opportunities for their residents and offer significant benefits including access to goods to numerous job opportunities. At the same time, high population areas can lead to tensions between demographic groups, as well as environmental strain. While the population of urban dwellers is continuing to rise, sources of social strain are rising along with it. The ultimate challenge for today’s urbanites is finding an equitable way to share the city’s resources while reducing the pollution and energy use that negatively impacts the environment.

### Section Quiz


### Short Answer


### Further Research

Interested in learning more about the latest research in the field of human ecology? Visit the Society for Human Ecology web site to discover what’s emerging in this field.
Getting from place to place in urban areas might be more complicated than you think. Read the latest on pedestrian-traffic concerns at the Streetsblog web site.

### References

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Burgess, Ernest. 1925. “The Growth of the City.” Pp. 47–62 in The City, edited by R. Park and E. Burgess. Chicago: University of Chicago Press.
Chandler, Tertius and Gerald Fox. 1974. 3000 Years of Urban History. New York: Academic Press.
Dougherty, Connor. 2008. “The End of White Flight.” Wall Street Journal, July 19. Retrieved December 12, 2011 (http://online.wsj.com/article/SB121642866373567057.html).
Feagin, Joe, and Robert Parker. 1990. Building American Cities: The Urban Real Estate Game. 2nd ed. Englewood Cliffs, NJ: Prentice Hall.
France24. 2010. “Sarkozy Promises War without Mercy for Paris Suburbs.” France 24, April 10. Retrieved December 9, 2011 (http://www.france24.com/en/20100420-sarkozy-war-suburbs-drugs-crime-violence-truancy-tremblay-en-france-saint-denis-france).
LeBlanc, Adrien Nicole. 2003. Random Family: Love, Drugs, Trouble and Coming of Age in the Bronx. New York: Scribner.
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Park, Robert. 1936. “Human Ecology.” American Journal of Sociology 42:1–15. 
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Sciolino, Elaine, and Ariane Bernand. 2006. “Anger Festering in French Areas Scarred in Riots.” New York Times, October 21. Retrieved December 11, 2011 (http://www.nytimes.com/2006/10/21/world/europe/21france.html?scp=2&sq=paris+suburb&st=nyt).
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United Nations, Department of Economic and Social Affairs, Population Division. 2018. "68% of the world population projected to live in urban areas by 2050, says UN." May 16, 2018. (https://www.un.org/development/desa/en/news/population/2018-revision-of-world-urbanization-prospects.html)
United States Census Bureau. 2014, "2010 Census Urban and Rural Classification and Urban Area Criteria." Retrieved December 16, 2014 (http://www.census.gov/geo/reference/ua/urban-rural-2010.html). 