As a native South Carolinian who spent most of my life in the Pacific Northwest (Oregon) I cannot agree with the linguist from that link. I hear distinct differences between "cot" and caught," etc. My relatives have a much stronger accent (pronounced "akseyunt")than do old-time Northwesterners. I suspect the professor interviewed newcomers, not old-timers.
Newcomers bring their accents with them and they reflect the speech of their peer group as well. If their leader's from Boston, pretty soon they'll all sound like Click and Clack, no matter where they're from.
Very interesting, Tinman. But I thought it was a given that everyone has an accent. After all, those from NY, for example, see their accents as normal so wouldn't they think we have an accent? It just seems to make sense to me.
Many years ago, there was a radio program which featured a man who would listen to audience members and then attempt to name their state of origin from their accents. He was often quite specific and supposedly very accurate. I wasn't totally convinced that it wasn't a set-up until I became better acquainted with regional variations. Then I realized just how good he was, assuming it wasn't a set-up.