Although the United States is an international melting pot and the average American makes a dozen moves in a lifetime, regional accents are alive and well. In fact, regional accents are becoming stronger and more different from each other, says William Labov, a professor of linguistics at the University of Pennsylvania in Philadelphia, although it’s not entirely clear why.

One possibility, says Labov, is that these original sound differences are being exaggerated, like trains moving in opposite directions on two railroad tracks. “The other is that dialect differences have become associated with political differences, so that the Blue States/Red States division comes close to the boundary between the Northern and Midland dialects,” he explains.