Social tensions were exacerbated by the revival of the Ku Klux Klan after 1915. The Tulsa race massacre broke out in 1921, with White mobs attacking Black people and carrying out a pogrom in Greenwood. In one of the costliest episodes of racist violence in American history, sixteen hours of rioting resulted in 35 city blocks destroyed, $1.8 million in property damage, and a death toll estimated to be as high as 300 people. By the late 1920s, the Ku Klux Klan had declined to negligible influence within the state.