My knowledge of the US is very limited but that's not what I've seen, for the me the "integration" in the US seems not very deep. At least in France in Paris there is a mixed middle class, the diversity in the workplace is huge at every level (well ok except for developers, even if there is a lot of CS grads the majority goes to consulting), there is a common culture and group of friends and colleagues are diverse without even noticing it without conscious thinking.

Sorry for the edits, I'm not a good english speaker and the tone wasn't right.