The suburbs of Denver, Boston, Philadelphia and San Francisco are home to the highest percentage of college graduates in the country, while fewer than one in eight residents of large swaths of Appalachia and the rural South have attained college degrees.

That’s according to this great map using data from the Census Bureau’s American Community Survey, which visualizes counties by the percentage of citizens who have attained bachelor’s degrees.

Source: @MetricMaps, which is still in the process of putting together its website.

The best-educated counties have a few things in common: They’re home to big universities, and they’re almost all suburban; notice the Research Triangle in North Carolina, two well-educated counties in Kansas near Lawrence and the University of Kansas, and Benton County, Ore., home of Oregon State. The two best-educated counties in Florida are centered on the University of Florida, in Gainesville, and Florida State, in Tallahassee; the same is true in Iowa, where Ames and Iowa City anchor the two best-educated counties.

The two exceptions are Washington, D.C., where educational attainment is one of the highest in the nation, and Boston and its environs, home to dozens of universities.

Here’s another correlation: The best-educated counties are also those with the highest median incomes. Here’s that map, using Census data compiled by Esri, Inc., a commercial mapping company:

Source: Esri, Inc.

Click here to get a look at an interactive version of the median income map.