American Dialect Maps

One of the few quibbles I have with the Atlas of North American English (or, at least the free maps available on their web page) is the lack of detail on the Southern part of the country.  Rick Aschmann's North American English Dialect map, goes a long way to correcting this.  From what I gather, he used youTube videos to assemble a poster size map of dialects based mostly on the pronunciation of vowels (which is the same feature ANAE uses as well).

The associated web page has a lot of background material and clear explanations, making this useful for people other than linguists who are interested in why accents sound the way they do.