How this got modded 5 insightful is beyond me. I've lived in cosmopolitan societies for a long time, one thing I've noticed that all races tend to stick together, the more of one kind in one place tends to let other kinds know in many ways they are not welcome. Disagree? Prove me wrong. Those that are tolerant like that naive person I am replying to are in a minority.
Unless you think that your gene-pool and culture should disappear, the struggle of your ancestors to go in wane, support unchecked immigration, because that is precisely what is going to happen, and it won't take all that long either. Mark my words.