American linguistic diversity as a whole isn’t dying—it’s thriving. Despite our gut-level hunch about the direction of the language; despite the fact that three-minute, off-peak, coast-to-coast long-distance calls that cost four inflation-adjusted dollars in 1970 are now free; despite cheap travel, YouTube, and the globalization of film and television, American dialects are actually diverging.

There are multiple examples of such divergence. But none is as dramatic, as baffling to linguists, and as mysteriously under the collective radar as what’s happening in the cities that ring the Great Lakes. From Syracuse, N.Y., in the east to Milwaukee in the west, 34 million Americans are revolutionizing the sound of English. Linguists first noted aspects of the change in the late 1960s. In 1972, three linguists, led by William Labov of the University of Pennsylvania, christened the phenomenon the Northern Cities Vowel Shift or, more simply, the Northern Cities Shift (NCS). What they observed may be the most important change in English pronunciation in centuries.

Northern Cities Vowel Shift: How Americans in the Great Lakes region are revolutionizing English. – Slate Magazine. Nothing has ever made me want to move back down South more than this article.