Which U.S. city has the most exurban areas around it? You know exburbs, those fast-growing but still semi-rural counties that lie near metropolitan areas but out beyond the suburbs?

It's not L.A.  Or Atlanta.  Or DC or Houston or Vegas.

Nope, it's Louisville, Ky., which is surrounded by 13 exurban counties, according to a recent Brookings Institution report. One of those counties, Crawford County, Indiana, has the nation's highest percentage of commuters who leave for work before 6 a.m. (Yikes!)