You need to define what unified means, without that your comments are unclear. In many big cities there is one school district, but the school you go to is basi

You need to define what unified means, without that your comments are unclear. In many big cities there is one school district, but the school you go to is basically defined by the area you live in, you go to a school near your house. Thus you end up with segregated schools if you have segregation by race or income (ie rich people live in expensive housing that is grouped, and that school has better educated parents and they can give more support to it). You need to add integrated to that equation. I went to a school that was historically racist with clear separation in schools that reflected neighborhood separation. At some point there was court ordered integration - and that was a really good thing. Over time, after I left the area, richer and whiter people either moved out of the city to the county schools and/or sent their kids to private schools, so the old segregation was re-introduced.