I'm actually curious if there are greater cultural differences between Americans of different races (say black-white) than between Europeans from different countries but same class.
As an American who has a decent amount of interaction with Europeans:
It's much easier to interact with Europeans of similar class to me than it is local people across class boundaries.
This is anecdotal, but as a knowledge worker and an atheist living in the American south, it just feels like there is often an "unbridgable gap" with less well-educated folk around here.
Which speaks to the fact that America is culturally balkanized. I mean, yes, "nigger" was a very popular search term right when Obama was elected... that's because there's a small, distinct group of Americans, say 5%, that are very ignorant racists.