In Board of Education of Oklahoma City v. Dowell, U.S. 111 S.Ct. 630, 638, 112 L.Ed.2d 715 (1991), the Supreme Court explained that a State's dismantlement of a segregated public education system--that is, the achievement of a "unitary" system--is complete when the State terminates its policy of intentional discrimination, adopts race-neutral policies and practices, and eradicates, to the extent practicable, the vestiges of unlawful discrimination.