What causes different accents within a country/region?

Question

Take the United States for example. You have a Northern accent, a Southern accent, a Midwest accent, etc. And then to make it worse you have accents within accents. There are very different accents when you are talking with a person from Louisiana and a person from Mississippi and a person from Texas. On the other hand New Yorkers have a different accent from New Jersey. Why and how do the different accents come about? I know my son, who was born and raised in the deep south has been living in Mass for the last 2 years, and I have noticed he is starting to really pick up their accent.

Answer 1

A measure of isolation, not meaning necessarily complete isolation, and sometimes different origins for much of the population.  That latter point is significant for the differences between Manchester and Liverpool in Lancashire.  They're only around thirty miles apart but the typical accents are remarkably distinct.  That has much to do with the amount of Irish immigration into Liverpool.

Answer 2

The accents are from the original people and there countries from which they came when they either started or already was speaking English. All followers into these regions then pick it up though assimilation's