Geographers Alasdair Rae and Garrett Nelson used commuting data from the American Community Survey to identify “megaregions” in the United States:
The emergence in the United States of large-scale “megaregions” centered on major metropolitan areas is a phenomenon often taken for granted in both scholarly studies and popular accounts of contemporary economic geography. This paper uses a data set of more than 4,000,000 commuter flows as the basis for an empirical approach to the identification of such megaregions.
