The sampling taken for each location is very faulty because it is largely from those in the public limelight. Those people who spend so much time in the public view very frequently alter their speech patterns quite a bit; sometimes to diminish, sometimes to accentuate their accents and speech patterns.
Native American dialects have been ignored on this site, and they are very prominent in Oklahoma.
CinnamonGirl, I have spent quite a bit of time on the dialect site and seems that I cannot get away from it. It is fascinating! I have read through it to the bottom and am now following the links of interest on specific subjects. Your posting of this link has made my weekend.