School segregation - by class

Americans are used to schools being by race. It seems we accept it and expect it...

Marginal Revolution: U.S. fact of the day

... American schools are more segregated by race and class today than they were on the day Martin Luther King, Jr. was killed, 43 years ago. The average white child in America attends a school that is 77 percent white, and where just 32 percent of the student body lives in poverty. The average black child attends a school that is 59 percent poor but only 29 percent white. The typical Latino kid is similarly segregated; his school is 57 percent poor and 27 percent white. Overall, a third of all black and Latino children sit every day in classrooms that are 90 to 100 percent black and Latino...

I'm interested in how segregated schools are by class -- including private schools. I'm not sure how to measure it, but my suspicion is that the kids of the top 5% no longer mix with the bottom 95%.

In a related vein, one of the great scandals of American society is that most public schools are funded by local taxation. It's appalling, but Americans seems to accept it without question.