Julie Sedivy summarizes recent work by William Labov: there is evidence that the spread of a vowel shift that’s working its way through the northern parts of the Rust Belt (sort of an Albany-Buffalo-Detroit-Milwaukee axis) is being curbed by more conservative speakers to the south and west.
Are we moving toward an era where Americans will speak discernibly red versus blue accents? It’s hard to say…. But I suspect that political ideology may become an anchor for accents to the extent that large social groups collectively identify themselves by their political beliefs….
So perhaps it’s not surprising that George W. Bush acquired a distinct Texan accent, despite having abundant exposure to people from the Northeast, or why Barack Obama sprouted a mild set of Chicago vowels, even though he was fully an adult before ever living there.