It's more than that. Jews, Asians (individually, Chinese, Koreans, Vietnamese, etc), Italians, Polish, Irish, Arabic ... all segregated into their own neighborhoods. The "melting pot" was never really real. We are a nation of immigrants that never really got along with one another except when common interests were threatened.

I don't know that it's uniquely American thing either, I think this happens anywhere that different cultures come together. Humans are deeply tribal.