Blue Counties in the South

Below is a map showing the southeastern US and which counties voted for Romney (red) versus which voted for Obama (blue).

Ignoring greater Miami and the infrequent, isolated outliers, all of the blue counties seem to be in a swath extending from the Chesapeake Bay in Virginia to and then down the Mississippi River.

Want to guess why?

If you were to conclude that those blue counties have a higher concentration of black / African-American voters than the other counties of the South, you would be right.

But the question then becomes, Why do those counties have more black residents than their neighbors?

The answer was described in a great article in The Atlantic a few months back. Ask if you're interested.