Regional Cultures Depend on a Period Without Immigration

Michael Barone, in his excellent Shaping Our Nation, notes that New England did not have a significant influx of non-Puritans from the 1620s to the 1780s. As a result, the Yankees developed a  strong regional culture.

I think this is a powerful, and generalizable, idea:  regional culture depends on a long period without significant in-migration.

The advantage of such a situation is that the local culture has time to develop and become pervasive.  The disadvantage is that the region can become backward.  Such a region misses out on the energy of new immigrant groups.  Worse, it misses out on the vibrant innovation that a mixed region must develop as it hybridizes old and new cultures into a new synthesis.

Low in-migration can account for why colonial New England developed such a strong regional culture. I think this also accounts for why the South developed such a distinctive culture up to the 1960s, and why Appalachia is distinctive to this day.