This article describes the population forces that caused U.S. metropolitan areas to grow rapidly after 1940 but caused falling population in many large older cities. It shows why the basic processes that generated the spatial growth and development of American metropolitan areas have also undermined the fiscal strength of many older central cities and inner-ring suburbs. By concentrating low-income households in inner-core neighborhoods, these processes create undesirable conditions that motivate economically viable households and firms to move to surrounding suburbs and not move back. Three strategies have been suggested for improving these conditions: major structural reform of metropolitan institutions, limited reform of big-city governments, and community development of inner-core areas. The first is the most capable of changing the dynamics causing decline, but it lacks political support because it would require the majority of metropolitan residents to sacrifice some benefits they gain from existing arrangements.