AT 5:08 A . M . O N J U N E 1, 1921,

a whistle pierced the predawn quiet of Tulsa, Oklahoma. There was disagreement later about whether the sound came from a steam engine on the railroad tracks or from a factory in the center of the booming oil town, but there was no doubting its meaning. It was the signal for as many as 10,000 armed white Tulsans, some dressed in Army uniforms from their service in World War I, to attack the place known as Greenwood, the city’s uniquely prosperous African American community. “From every place of shelter up and down the tracks came screaming, shouting men to join in the rush toward the Negro section,” a white witness named Choc Phillips later remembered. By dawn, “machine guns were sweeping the valley with their murderous fire,” recalled a Greenwood resident named Dimple Bush. “Old women and men and children were running and screaming everywhere.”