Subways and Urban Growth: Evidence from Earth∗

We investigate the relationship between the extent of a city’s subway network, its population and its spatial configuration. To accomplish this investigation, for a sample of the 632 largest cities in the world, we construct panel data describing the extent of each of the 138 subway systems in these cities, their population, and measures of centralization calculated from lights at night data. These data indicate that large cities are more likely to have subways, but that subways have at most a small effect on urban population growth. Consistent with economic theory and with other studies of the effects of transportation improvements on cities, our data also indicate that subways cause cities to be more decentralized.