The problem is local funding for schooling I think. If funding was state level or federal and funds would be allocated to schools that need it - I.e. schools with poor students (less help from home, perhaps language issues) will be given a lot more funding per student.

Without this, what happens is that affluent people move to good school districts. These districts then get students with better academic backgrounds, fewer parents with drug/legal problems, fewer students with lanugage problems. Its pretty obvious to be a system that spirals out of control in just a few generations, creating segregated patches.

But perhaps this is how the support for the public school system is upheld? Rich people accept the system, because they can game it? If that's the case then it might be a necessary evil. Politically viable alternatives such as voucher systems will create the same effect (I know from experience).