I got a bit of that when I moved to SF. It's harder to pin Midwesterners down by accent, though (city folks, anyway).
I've found that it's the keywords that indicate where people are from within the Midwest:
Is it soda or pop? Is it car-mel or care-uh-mel?
(I do linguistic stuff in my day job.)
To my ear, the Chicago accent is represented but exaggerated in the "Bill Swerski's Superfans" sketches from SNL in the 1990s - "Da bearssss".
And it's "cur-muhl". :)