Sprawl

To study the evolution of urban land use across the entire continental us, we merge high-altitude photographs from the 1970s with satellite images from the 1990s. The resulting data set tracks changes in urban development for 30m×30m squares on a regular grid. This paper describes broad patterns evidenced by this data. Only 1.9% of the us was developed in 1992. About one-third of this developed area was not developed around 1976. We examine the spatial heterogeneity of development, and in particular how this varies with distance from earlier development, highways, and the shoreline. While most of the us remains undeveloped, undeveloped land is locally scarce in areas that are particularly salient to people. We also study the overall contribution to development of widely-emphasized phenomena such as leapfrogging and edge city development.