The Ku Klux Klan (KKK), a white supremacist organization, was founded in the United States in 1865. The group was known for its terrorist activities, including lynchings, beatings, and intimidation of African Americans, Jews, and other minority groups. At its peak in the 1920s, the KKK had an estimated membership of 4-5 million people and was considered a significant force in American politics.