Urbanization occurs when people move from rural to urban areas so that the proportion of people living in cities increases while the proportion of people living in the country diminishes. This migration is often motivated by economic factors. Indeed, the world's population has urbanized quickly. In 1900, just 13% of people lived in cities; by 1950, the proportion rose to 29%, and according to projections. By 2030, the proportion could reach 60%, or nearly 5 billion people. Figure 1
Urbanization generally occurs with modernization and industrialization. Modernization and industrialization pull people to cities at the same time that they push people from rural homes. A major contributing factor is known as "rural flight." In rural areas, often on small family farms, it is difficult to improve one's standard of living beyond basic sustenance. Farm living depends on unpredictable environmental conditions and in times of drought, flood, or pestilence, survival is difficult. In modern times, industrialization of agriculture has negatively affected the economy of small- and middle-sized farms and strongly reduced the size of the rural labor market.
As more and more people leave villages and farms to live in cities, urban growth results. The rapid growth of cities like Chicago in the late nineteenth century and Mumbai a century later can be attributed largely to rural-urban migration. This kind of growth is especially commonplace in developing countries. Urbanization occurs naturally from individual and corporate efforts to reduce time and expense in commuting and transportation while improving opportunities for jobs, education, housing, entertainment, and transportation. Living in cities permits individuals and families to take advantage of the opportunities of proximity, diversity, and marketplace competition. Due to their high populations, urban areas can also have much more diverse social communities than rural areas, allowing others to find people like them. Figure 2
Economic and Environmental Effects of Urbanization
Urbanization has significant economic and environmental effects on cities and surrounding areas. As city populations grow, they increase the demand for goods and services of all kinds, pushing up prices, especially the price of land. As land prices rise, the local working class may be priced out of the real estate market and pushed into less desirable neighborhoods.
Growing cities also alter the environment. For example, urbanization can create urban heat islands. Heat islands are formed when industrial and urban areas are developed and reduce the amount of land covered by vegetation or open soil. In rural areas, the ground helps regulate temperatures by using a large part of the incoming solar energy to evaporate water in vegetation and soil. This evaporation, in turn, has a cooling effect. But in cities, where less vegetation and exposed soil exists, the majority of the sun’s energy is absorbed by urban structures and asphalt. During the day, cities experience higher surface temperatures because urban surfaces produce less evaporative cooling. Additional city heat is given off by vehicles and factories, as well as by industrial and domestic heating and cooling units. Together, these effects can raise city temperatures by 2 to 10 degrees Fahrenheit (or 1 to 6 degrees Celsius).
Suburbanization and Counterurbanization
Recently, in developed countries, sociologists have observed suburbanization and counterurbanization, or movement away from cities, which may be driven by transportation infrastructure or social factors like racism. In developed countries, people are able to move out of cities while maintaining many of the advantages of city life because of improved communications and means of transportation. In fact, counterurbanization appears most common among the middle and upper classes who can afford to buy their own homes.
In the United States, suburbanization began in earnest after World War II, when soldiers returned from war and received generous government support to finance new homes. These young men were also interested in settling down, buying their own homes, and achieving independence and a less hectic daily life with a more affordable cost of living than they could find in cities. Thus, suburbs were built. Smaller cities located on the edges of the larger city, which often include residential neighborhoods for those working in the area. Suburbs grew dramatically in the 1950s when the U.S. interstate highway system was built, and automobiles became affordable for middle class families. Around 1990, another trend emerged, called "exurbanization." Upper class city dwellers moved out of the city, beyond the suburbs, to live in high-end housing in the countryside.
Suburbanization may be a new urban form. Rather than densely populated centers, cities may become more spread out, composed of many interconnected smaller towns. In any case, the history of suburbanization calls into question depictions of urbanization as a one-way process. Rather, the modern U.S. experience has followed a circular pattern over the last 150 years, from a largely rural country, to a highly urban country, to a country with significant suburban populations.