If you haven’t been already, go fill out this Harvard professor’s online dialect survey. Make sure you have a lot of time to waste; it’s long, but it’s well worth it to find out that your fellow Americans have fifteen different phrases for the crap that you find in the corner of your eye when you wake up in the morning. (That’ll show those snooty eskimos, with their 300 words for snow.)
Check out the maps especially, though they are less illustrative than I would have hoped. The use of modals (“might could”), for example, seems to have less locational correlation than I thought. You have to wonder how much this is influenced by Internet use demographics. (I figure not only are Internet users more likely to be mainstreamed for their education, they’re also more likely to have moved away from their linguistic base.)
You also come to suspect that the maps reflect the population density of the US more than they do dialects. Still they seem to confirm the lament of folks as far back as Steinbeck and before that America is losing its regional linguistic charms.