Southern accents, Eastern accents, Northern accents and Ebonics

[SWTXBelle]

What you are talking about is really linguistics - which is fascinating. Language is never static. I think that media saturation and technological advances means it can do so at a faster rate than before, certainly. And some types of slang and colloquial speech are no longer geographically limited in the way it was before. So, a catchphrase on a television show can sweep the country almost overnight.
On what I consider a positive note, linguists have been surprised at the entrenched nature of regional accents and speech. There was a theory that tv would erase such differences. But it hasn't happened.