Ku Klux Klan , designation mainly given to two distinct secret societies that played a part in American history, although other less important groups have also used the name. The first Ku Klux Klan was an organization that thrived in the South during the Reconstruction period following the Civil War . The second was a nationwide organization that flourished after World War I. Subsequent groups calling themselves the Ku Klux Klan sprang up in much of the South after World War II and in response to civil-rights activity during the 1960s.
