(GMT)13 SEP 2016 VISWI00:
What a great work this is...The web site 'North American English Dialects, Based on Pronunciation Patterns' is being updated by an individual.
There are even some audio and video sample. Visit the link and find more interesting information.
'For many of the cities or towns on this map, you can listen to an audio or video sample of speech of a native (more specifically, someone who was raised there, though not necessarily born there, and whose dialect clearly represents that place). All of the cities or towns with a green center have such an audio or video sample that can be listened to (and a few of the ones with pink centers do also)'