I have heard of this happening in private schools, yes. But there is A LOT of racism where I live. Blacks don't want to be around whites and whites don't want to be around blacks.
When I went to high school, there were only 5 Mexicans and they ALWAYS put us in the same classes together according to our grade. But everyone else was spread out pretty evenly. All the Mexicans, including myself, were honor students. Most people at school thought I was Asian. I still look Asian lol but I'm mostly Native American.
In the colleges and universities, most people going to college are black and whites go to the university nearby.
I do know that the blacks around here like to stick together. I have heard quite a few of them say this. It has actually benefited them doing this. When they feel discriminated against they band together.
I will say that there are clinics and hospitals around here where it is hard to find different races working together.
Segregation was actually still practiced well into the millenium. I'm still afraid to go into certain areas because people still believe in segragation. But I know which areas to avoid.