At a meeting in February 2005, scores of parents from the two majority white elementary schools complained of overcrowding and discipline problems in the middle school their children were sent to outside of the northern enclave.

Ms. Tucker said she, another board member and a teacher were the only blacks present. The white parents clamored for a new middle school closer to their homes. They also urged Dr. Levey to consider sending some students being bused into northern cluster schools back to their own neighborhood, Ms. Tucker said. Dr. Levey did not dispute the broad outlines of Ms. Tucker’s account.

“That was the origin of this whole rezoning,” Ms. Tucker said.

Months later, the school board commissioned a demographic study to draft the rezoning plan. J. Russell Gibson III, the board’s lawyer, said the plan drawn up used school buildings more efficiently, freeing classroom space equivalent to an entire elementary school and saving potential construction costs of $10 million to $14 million. “That’s a significant savings,” Mr. Gibson said, “and we relieved overcrowding and placed most students in a school near their home. That’s been lost in all the rhetoric.”

Others see the matter differently. Gerald Rosiek, an education professor at the University of Alabama, studied the Tuscaloosa school district’s recent evolution. “This is a case study in resegregation,” said Dr. Rosiek, now at the University of Oregon.

Image The rezoning plan will force an estimated 880 students in Tuscaloosa to change their schools. Credit... Dave Martin for The New York Times

In his research, he said, he found disappointment among some white parents that Northridge, the high school created in the northern enclave, was a majority-black school, and he said he believed the rezoning was in part an attempt to reduce its black enrollment.

The district projected last spring that the plan would move some 880 students citywide, and Dr. Levey said that remained the best estimate available. The plan redrew school boundaries in ways that, among other changes, required students from black neighborhoods and from a low-income housing project who had been attending the more-integrated schools in the northern zone to leave them for nearly all-black schools in the west end.