This study details a new effort to locate and describe the exurbs of large metropolitan areas in the United States. It defines exurbs as communities located on the urban fringe that have at least 20 percent of their workers commuting to jobs in an urbanized area, exhibit low housing density, and have relatively high population growth. . . . Despite their popularization by political analysts, media, and local growth activists, the “exurbs” do not abound nor fit a single, neat stereotype. Just 6 percent of large metro area residents live in an exurb, and these exurbs vary from affordable housing havens for middle-class families, to “favored quarters” for high-income residents, to the path of least resistance for new development. While they may continue to capture interest among political observers, the real test for exurbia lies in how our nation accommodates future growth. Will exurbs remain exurbs or become the suburbs of tomorrow?