Both the
Post and
Times had Sunday articles discussing the Asian American community in Atlanta. The Post had a map showing its recent growth, which was concentrated in certain areas.
What struck me was the likelihood that the concentration mostly reflected the choice of the immigrants, the desire to live in areas with people with whom you might share something. (Since "Asian-American" covers some 20 countries or so, you might not be able to speak your neighbor's language, but presumably you might have neighbors more accepting of you than in a 95 percent white, or 95 percent black, community.)
It's always hard to untangle the factors behind residential concentrations (I almost wrote "segregation" but concentration is the better term.) All other things being equal, a person might decide where to live based on the likelihood of finding people with similar backgrounds, tastes, opinions, values, or based on the fear of having to deal with strangers.
Then moving from the viewpoint of the person moving into a residence to the viewpoints of the potential neighbors you bring up other factors. I'd venture that in most cases in today's America the weight of the emotion involved is heavier on the side of the mover, than on the side of the neighbors.
Back in the day we had "lily-white" areas, so someone moving in of a different race could cause the potential neighbors to have a lot of emotion. I don't think we have "lily-white" areas much these days, so there's less emotion. Where you get emotion is NIMBYism, questions of zoning in particular.