I actually posted Rick Aschmann’s dialect map back in 2011, but although it’s just as ugly there’s plenty of new information, and I figure a lot of people didn’t see it back then, so here it is again; besides the map in its various forms, there are a Guide to the Sounds of North American English and Special Interest and Historical Articles (e.g., The Cot-Caught Merger and The Father-Bother Distinction; scroll around the page and who knows what you’ll find. Thanks, Terry!
“Just as ugly” sums it up. The author could learn something (a lot, really) from Edward Tufte.