I think it is on the History channel and it was a series. The title doesn't tell you what it was about, I was expecting something different when I watched it. I will look at the listings and see if it is still there. It was this past spring/summer I think. They did the whole USA and how people got their accents/dialects.

Found it H2 season 2 How the states got their shapes(I said the title was different than content) MOUTHING OFF is the name of the episode aired 7/12/2012