This parallels closely my experiences at a certain UC in the bay area.
It was ironic because for a school that preaches diversity, for a student body that is self-proclaimed ultra liberal and progressive, it was socially very conservative. The better off white kids hang out pretty much with only other better off white kids in their frats..the asians have their own frats..so do the blacks and hispanics. What's more, there is not too much interaction between these groups to the point where you can really feel uncomfortable if you find yourself in a group where you don't belong.
I don't really know where I was going with this, other than people definitely tend to form cluster of like-minded people.