Now I live in the northern part of Brooklyn where a lot of African Americans and Jewish people live. I found that people usually live in communities composed of the same ethnic group. When I took the subway (3 line), I sometimes found that there are only African Americans and Jewish people, and no Asian people on the train. I felt little uncomfortable there.
There is a Japanese community in NY Japanese people gather there, so you can buy Japanese language books and foods in NY. You can even eat Ramen there. To be honest, I felt pleasant when I visited the East Village where there are a lot of Japanese people and Japanese stores which were familiar to me. I can understand the reason why people live in their ethnic communities.
Salad bowl (cultural idea)
In the salad bowl model, various American cultures are juxtaposed — like salad ingredients — but do not merge together into a single homogeneous culture. Each culture keeps its own distinct qualities.
I think that the Salad bowl concept describe New York city situation well.