photo: The KKK marches down Pennsylvania Avenue in Washington, D.C. in 1926.

Archive from FBI.gov

Contributing to criminal chaos of the 1920s was the sudden rise of the Ku Klux Klan, or KKK. In the early 1920s, membership in the KKK quickly escalated to six figures under the leadership of “Colonel” William Simmons and advertising guru Edward Young Clarke. Robed members of the KKK marching down Pennsylvania Avenue in Washington, D.C., with American flags and the U.S. Capitol in the background.

By the middle of the decade, the group boasted several million members. The crimes committed in the name of its bigoted beliefs were despicable—hangings, floggings, mutilations, tarring and featherings, kidnappings, brandings by acid, along with a new intimidation tactic, cross-burnings. The Klan had become a clear threat to public safety and order.