Essays on the spatial distribution of population and employment

Between 1950 and 1990, the aggregate population of center cities in the U.S. declined by 16 percent despite national population growth of 64 percent. The first chapter of this dissertation assesses the extent to which the construction of new limited access highways has contributed to center city population decline. Using planned portions of the interstate highway system as a source of exogenous variation, empirical estimates indicate that the population living in center cities would have grown by 6 percent had the interstate highway system not been built. Calibrations of a land use and commuting model imply that one new highway passing through a center city reduces the center city population by about 18 percent, a magnitude that is consistent with estimates from the data. Further, observed changes in the spatial distribution of the population in metropolitan areas following new highway construction are consistent with theoretical predictions from the model.; One implicit assumption in the model used to motivate the empirical work in Chapter 1 is that all employment occurs in central business districts. Chapter 2 presents land use data demonstrating that this assumption is a strong one. In 1990 less than 50 percent of metropolitan area employment was located in center cities with a significant fraction located in peripheral subcenters. Chapter 2 proposes a model that endogenizes the location of employment and population in a metropolitan area simultaneously. The model employs a production externality that pushes firms to locate together and emphasizes the value of workers' travel time as a mechanism to keep the metropolitan area spatially unified. The model generates polycentric equilibria endogenously. Using a developer equilibrium concept, simulations of the model show that equilibrium subcenter location implies more dispersed employment than is optimal.