I'd say that the US has about 8 distinct genres of accent:

To which I would add, "and only one speed: Excruciatingly slow" - at least for Antipodeans. No matter whence in the US, or Canada, they come, North Americans whose first English is English seem to take a week to finish a salutation. In the early 1980's, the NZ tourist board put together a promtional video narrated by one of our most popular newsreaders, a man noted for his careful enunciation. When it aired in the US, stations which carried it were apparently inundated with complaints that he was talking far too fast!