Cities have been pivotal role to improved living standards, because of the opportunities they facilitate. This is particularly evident over the past two centuries, as world urbanization has risen from 3 percent to over 50 percent, and to more than 80 percent in the United States.
The fortunes of U.S. core cities (municipalities) have varied greatly in the period of automobile domination that accelerated strongly at the end of World War II. This is illustrated by examining trends between the three categories of “historical core municipalities” (Figure 1). Since that time, nearly all metropolitan area (the functional or economic definition of the city) growth has been suburban, outside core municipality limits, or in the outer rings of existing, core municipalities.