I live in Lafayette, which is about 2 hours west of New Orleans.

Believe it or not, I can sometimes hear a Baton Rouge accent and even a Broussard (small town by lafayette) accent. The differences between these are much more subtle than a N'awlins, NYC, or Boston accent, but they are still unique in their own way.

I think people just tend to talk like the people they have always been around, and in places where the same families have lived for generations it develops it's own characteristics and becomes known as an accent. In California, where everyone is a clone of a celebrity, everybody speaks plainly because it's a mixture of many different cultures - it seems like most people move to California, instead of having been born and raised in California along with their ancestors. Now that I think of it, I believe the definition of a cracker is someone who has no accent at all.