That's really cool, Father Steve; thanks for posting it.

These days, Labov found, the most extreme dialect change in the country is taking place in the Chicago area. “The ‘eah’ sound, which you hear in ‘happened’—heahppened—is a young, very invasive sound that is rapidly changing a number of other sounds around it,” he said. This so-called “Northern Cities Shift” is spreading toward St. Louis along I-55, transforming the Inland North dialect, which used to be the model for standard American pronunciation.
I had no idea, and ...I wonder why it's changing. Fascinating that it's along an interstate highway--do that many people regularly run up and down between Shy-town and St. Louis?

Re:
locals in such areas as northern Ohio and Michigan traditionally spoke precise English because they wanted to distinguish themselves from the speakers of Southern dialects in their states This may also (as he said in another part of the article) be due to class: a lot of poor people from Kentucky and southern Ohio went up there hoping to find work in the early-middle part of the 20th. century. Usually Detroit because of the auto factories there.