This interactive map lets you see how college education has developed in the United States, and where you live.
My county, for instance, has tracked the national average almost exactly, going from 4.6 percent to 28.7 percent. It's fascinating to look at the pockets of higher education that dot the country. Loudon County, Virginia, seems to be the highest percent in the country (though mention in the comments if you find a larger one) at 56.47 percent. Loudon County, part of the Washington, D.C., metro area, also has the the highest income per capita of any county in America. You could spend all day finding these types of connections.
View the map here.