Though James Dent could watch Central High School’s homecoming parade from the porch of his faded-white bungalow, it had been years since he’d bothered. But last fall, Dent’s oldest granddaughter, D’Leisha, was vying for homecoming queen, and he knew she’d be poking up through the sunroof of her mother’s car, hand cupped in a beauty-pageant wave, looking for him.

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 […]