In 1940, a mere 4.6 percent of Americans had college degrees. Today, that number is nearly 28 percent. The Chronicle of Higher Education has created a fun interactive map that allows you to track the number of college degrees over the last 70 years by county, sex, and race. You can watch the map play and see how college education has developed around you.
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.