You've hit the nail on the head. One reason there are so many red-zoners on the outskirts of major cities: thirty years of federal-court-ordered forced bussing. People who didn't want their children bussed moved into neighboring counties, out of the reach of the dictatorial judges. After awhile, these 'exurban' areas became seen as great places to raise a family, and young people planning families moved there from the start.
Yeah, but the suburbs in the northeast vote Democratic as well, albeit in not as large numbers as the cities.