The question that has perhaps divided students of vouchers more than any other is their likely effect on the social and economic class structure. Some have argued that the great value of the public school has been as a melting pot, in which rich and poor, native- and foreign-born, black and white have learned to live together. That image was and is largely true for small communities, but almost entirely false for large cities. There, the public school has fostered residential stratification, by tying the kind and cost of schooling to residential location. It is no accident that most of the country's outstanding public schools are in high-income enclaves.