The forces that produced a hundredfold increase in urban population in the United States between 1800 and 1900 included national population growth, increased agricultural productivity, the growth of factory production, and the development of low-cost modes of transportation. The nature of nineteenth-century transportation contributed to an extremely dense pattern of urban development.
In the late nineteenth century, the first signs of suburbanization became visible as the electric streetcar began expanding the old "walking city." In the twentieth century, automotive transportation, electronic communications, and increased income promoted massive suburbanization of population and economic activity, which continue to the present time.
We noted the slowdown of central-city population growth in the decades after World War II and the declines in the population of many of the largest cities, particularly inland industrial cities such as Cleveland and St. Louis. But at the same time that central-city growth slowed, the total population of metropolitan areas continued to grow rapidly.
In the post-World War II period, central cities have grown poorer relative both to the suburbs and to nonmetropolitan areas. The selective outmigration of more prosperous households and the loss of employment to suburbs, nonmetropolitan areas, and overseas competitors have contributed to this trend. Another factor was the migration to the cities of a large, generally poor population pushed off the land by the rapid mechanization of agriculture in the decades after World War II.
We noted that from 2000 to 2010 the population shrinkage in larger central cities slowed considerably and that one factor behind this may be the changing age structure of the U.S. population. The chapter closes with the possibilities of a reversal of the decentralizing trends which have predominated since the end of World War II and a turn toward a more urban pattern of development.