TUSCALOOSA, Ala. — After white parents in this racially mixed city complained about school overcrowding, school authorities set out to draw up a sweeping rezoning plan. The results: all but a handful of the hundreds of students required to move this fall were black — and many were sent to virtually all-black, low-performing schools.

Black parents have been battling the rezoning for weeks, calling it resegregation. And in a new twist for an integration fight, they are wielding an unusual weapon: the federal No Child Left Behind law, which gives students in schools deemed failing the right to move to better ones....

Tuscaloosa, where George Wallace once stood defiantly in the schoolhouse door to keep blacks out of the University of Alabama, also has had a volatile history in its public schools. Three decades of federal desegregation marked by busing and white flight ended in 2000. Though the city is 54 percent white, its school system is 75 percent black.