ABSTRACT
After the Industrial Revolution, in addition, population growth was accompanied by a rise in the number of cities and ultimately an urban way of life that now pervades all industrial societies. Decreasing death rates are a major cause of excessive population growth in Third World nations. Urbanization as a population movement is continuing: in the United States, as already noted, approximately 80 percent of people live in urban areas. In the United States, which is already a pre-eminently urban society, many cities are, or have been, in some form of crisis situation. Whereas originally suburbanization was a movement of white persons of middle-class or upper-middle-class background, leading to a high degree of racial segregation, minorities have also flocked to the suburbs since the 1970s. In turn, large populations, the industrial system, and an urbanized lifestyle have wreaked havoc on the planet's environment. Populations and the physical and social structures they erect exist within the framework of a natural environment.
