So, at about 4:30 in the afternoon on October 18, Dent, age 64, made his way off the porch and to the curb along Martin Luther King Jr. Boulevard in the West End of Tuscaloosa, Alabama. Soon he could hear the first rumblings of the band.

There was a time, little more than a decade ago, when the Central High School homecoming parade brought out the city. The parade started in the former state capital's lively downtown and seemed to go on for miles. The horns of one of the state's largest marching bands, some 150 members strong, would bounce off the antebellum mansions along the streets. Revelers—young and old, black and white, old money and no money—crowded the sidewalks to watch the elaborate floats and cheer a football team feared across the region.

Central was not just a renowned local high school. It was one of the South's signature integration success stories. In 1979, a federal judge had ordered the merger of the city's two largely segregated high schools into one. The move was clumsy and unpopular, but its consequences were profound. Within a few years, Central emerged as a powerhouse that snatched up National Merit Scholarships and math-competition victories just as readily as it won trophies in football, track, golf. James Dent's daughter Melissa graduated from Central in 1988, during its heyday, and went on to become the first in her family to graduate from college.

But on that sunlit day last October, as Dent searched for Melissa's daughter in the procession coming into view, he saw little to remind him of that era. More caravan than parade, Central's homecoming pageant consisted of a wobbly group of about 30 band members, some marching children from the nearby elementary schools, and a dozen or so cars with handwritten signs attached to their sides. The route began in the predominantly black West End and ended a few blocks later, just short of the railroad tracks that divide that community from the rest of the city.

The reason for the decline of Central's homecoming parade is no secret. In 2000, another federal judge released Tuscaloosa City Schools from the court-ordered desegregation mandate that had governed it for a single generation. Central had successfully achieved integration, the district had argued—it could be trusted to manage that success going forward.

Freed from court oversight, Tuscaloosa's schools have seemed to move backwards in time. The citywide integrated high school is gone, replaced by three smaller schools. Central retains the name of the old powerhouse, but nothing more. A struggling school serving the city's poorest part of town, it is 99 percent black. D'Leisha, an honors student since middle school, has only marginal college prospects. Predominantly white neighborhoods adjacent to Central have been gerrymandered into the attendance zones of other, whiter schools.

Tuscaloosa's schools today are not as starkly segregated as they were in 1954, the year the Supreme Court declared an end to separate and unequal education in America. No all-white schools exist anymore—the city's white students generally attend schools with significant numbers of black students. But while segregation as it is practiced today may be different than it was 60 years ago, it is no less pernicious: in Tuscaloosa and elsewhere, it involves the removal and isolation of poor black and Latino students, in particular, from everyone else. In Tuscaloosa today, nearly one in three black students attends a school that looks as if Brown v. Board of Education never happened.

In Tuscaloosa today, nearly 1 in 3 black students attends a school that looks as if Brown v. Board of Education never happened.

Tuscaloosa's school resegregation—among the most extensive in the country—is a story of city financial interests, secret meetings, and angry public votes. It is a story shaped by racial politics and a consuming fear of white flight. It was facilitated, to some extent, by the city's black elites. And it was blessed by a U.S. Department of Justice no longer committed to fighting for the civil-rights aims it had once championed.

Certainly what happened in Tuscaloosa was no accident. Nor was it isolated. Schools in the South, once the most segregated in the country, had by the 1970s become the most integrated, typically as a result of federal court orders. But since 2000, judges have released hundreds of school districts, from Mississippi to Virginia, from court-enforced integration, and many of these districts have followed the same path as Tuscaloosa's — back toward segregation. Black children across the South now attend majority-black schools at levels not seen in four decades. Nationally, the achievement gap between black and white students, which greatly narrowed during the era in which schools grew more integrated, widened as they became less so.

Resegregating U.S. Schools

APP: See the complete list of open and closed desegregation orders by school district »

In recent years, a new term, apartheid schools — meaning schools whose white population is 1 percent or less, schools like Central—has entered the scholarly lexicon. While most of these schools are in the Northeast and Midwest, some 12 percent of black students in the South and nearly a quarter in Alabama now attend such schools—a figure likely to rise as court oversight continues to wane. In 1972, due to strong federal enforcement, only about 25 percent of black students in the South attended schools in which at least nine out of 10 students were racial minorities. In districts released from desegregation orders between 1990 and 2011, 53 percent of black students now attend such schools, according to an analysis by ProPublica.

The Dent family, from grandfather to granddaughter, has lived out integration's fleeting wonder, a fact that hardened James Dent's face as he stood on that Tuscaloosa curb last October. The parade—just 15 minutes old, and yet almost over — quickly brought D'Leisha before him. Nene, as her family calls her, beamed and waved. Dent waved back and looked around to share the moment. But besides his wife and his stepson, no one else was there.