After Brown v. Board of Education (more on that below), America specifically ordered many school districts to desegregate (aka stop having just one type of person at the school). This was supposed to make it more likely that African-American kids would be in schools with non-African-American kids ... this is desegregation. It made it official: Separate but equal is unconstitutional. Turns out, our schools are even MORE segregated now. Even more separate.
This is a GIF of an interactive map, which you can interact with to your heart's content here.