Demography and population loss from central cities, 1950-2000

"The share of metropolitan residents living in central cities declined dramatically from 1950 to 2000. We show that, if not for a series of demographic factors - notably renewed immigration, delayed child bearing, and a decline in the share of households headed by veterans, who are eligible for military housing benefits - cities would have contracted even further over this period. We provide causal estimates of the relationship between the living in the central city and the presence of children in the household using the occurrence of twins as an exogenous event and of the relationship between the living in the central city and veteran status, relying on a discontinuity in the probability of military service during and after the mass mobilization for World War II. Demographic trends were only strong enough to stanch the flow of population from cities, not to generate an urban revival"--National Bureau of Economic Research web site.