General American is actually native to Iowa.
Really? Tell me more, I'm interested.
Here's the range of it traditionally:
It's a bit of a mystery to me why it became the standard--it's a fairly conservative dialect though, and so presumably it can straddle that line between other dialects.
Of course, now large swaths of its traditional range have gotten swallowed up by the
Northern Cities Vowel Shift, which, according to Wikipedia, has this distribution:
And it's gaining ground every day. English vowels tend to be ridiculously unstable from dialect to dialect, and several North American English dialects are undergoing vowel shifts of some type.
Poll
