I've spent the last 30 minutes staring at this picture of North American English dialects (excluding African American dialects, unfortunately, which is a whole other can of worms that I'm not going to discuss now but needs to be mentioned) that I found on the Sociological Images blog from my previous post. If I were to make any changes I'd move the line separating "South" from "Midland" up slightly so that it covered Portsmouth, Ohio. When I first moved to Columbus, it wasn't rare for people to mistake me for being from the Deep South. In fact, I recently visited my mother in Virginia Beach, VA, and couldn't even tell the difference between the accents there and in my hometown. My mom has lived there for years and her accent hasn't changed a bit, whereas mine completely went away after I'd been living in Columbus for a couple of years.
I'd also dip the pen/pin line down from around Mansfield so that it covered Columbus (I am not sure what samples he listened to but we definitely don't pronounce them the same here, although they do in southern Ohio). Or it might also be an island similar to Cincinnati. The dialect here sounds almost nothing like it does 45 minutes in any direction. He did get it very right that Cleveland and the surrounding areas are nothing like the rest of Ohio, but I think it is inaccurate to lump Columbus with the majority of the state.
What's very interesting to me is that south Florida is most similar to the Midland dialect. I'm not sure how to reconcile that, although my personal experience with people from Miami is that it is generally true (if you forgive the slight Spanish accent on some words). Also, of all places, the southern tip of New Mexico and the west corner of Texas?! I am honestly trying to figure this out, whether the interface with Spansh-speaking areas has anything to do with the Midwestern-izing of the English in the area. I don't have a clue.
If you live in a contentious area you can email the site creator with YouTube links of representative samples for your area. Really cool.