Here's a little secret I don't tell often: I love writing dialog.
Unfortunately, on a "typical" day as freelance commercial writer, writing dialog could be construed as "wasting time." So I was delighted (if you must know, I squealed) when I happened upon this little ditty on US dialects, broken down by state.
I was researching the history of the US furniture industry at the time.
That's right. My life really is a non-stop glam-fest.
Anyway, for you creative writers out there, follow these directions to the dialect survey: http://www4.uwm.edu/FLL/linguistics/dialect/maps.html