The Ku Klux Klan is America's oldest white supremacist organization. It first gained power in the South during Reconstruction (1865–77; the period following the American Civil War when the federal government assisted and policed the former Confederate states), which the Klan resisted with beatings, murder, and terrorism. Although the organization has splintered and its fortunes have declined somewhat, the Klan still maintained a hold on the American consciousness going into the twenty-first century.

The organization's name is derived from the Greek word kuklos, meaning "circle," and a corruption of "clan," or family. Its origins lie with a group of six Confederate war veterans who returned to Pulaski, Tennessee, when the Civil War (1861–65) ended in 1865. They relieved boredom by dressing up in white sheets and playing pranks on their neighbors by night. The Klan might have remained a mere gang of bullies were it not for...