In this (once again great) Frontline report, they examine the return to segregation in american schools:

Here in texas we have been watching the gradual change in the quality of education. Over the last 20 years, and even more recently it seems, even to a casual eye, that it is harder and harder to get a good education from a public school when you are in a large city. Inner city schools have not always been bad, but what is the reason that they are so poor these days, to the point where the middle class no longer believe in them, and those that are in them, feel stuck with them? What is it that make people believe that public schools aren’t even worth the effort in trying to save them?