The original Ku Klux Klan was created in the aftermath of the American Civil War by six educated, middle-class Confederate veterans on December 24, 1865 from Pulaski, Tennessee. They made up the name by combining the Greek "kyklos" (κυκλος,circle) with "clanIt was one among a number of secret, oath-bound organizations, including the Southern Cross in New Orleans (1865), and the Knights of the White Camellia.
"By 1872, the Klan as an organization was broken. In some areas, other local paramilitary organizations such as the White League, Red Shirts, saber clubs, and rifle clubs continued intimidation and murder of black voters
The second Klan 1915-1944
The second Ku Klux Klan was founded in Atlanta with a new anti-immigrant, anti-Catholic, and anti-Semitic agenda. The bulk of the founders were from an Atlanta-area organization calling itself the Knights of Mary Phagan that had organized around the Frank trial. The new organization emulated the fictionalized version of the Klan presented in The Birth of a Nation.
"The Klan's resurgence in the 1920s partially stemmed from the extreme militant wing of the temperance movement. In Arkansas, as elsewhere, the newly formed Ku Klux Klan marked bootleggers as one of the groups that needed to be purged from a morally upright community. In 1922, 200 Klansmen torched saloons that had sprung up in Union County in the wake of the oil discovery boom. The national Klan office ended up in Dallas, Texas, but Little Rock was the home of the Women of the Ku Klux Klan. The first head of this female auxiliary was a former president of the Arkansas WCTU.
In 1921, the Klan arrived in Oregon from central California and established the state's first klavern in Medford. In a state with one of the country's highest percentages of white residents, the Klan attracted up to 14,000 members and established 58 klaverns by the end of 1922. Given small population of non-white minorities outside Portland, the Oregon Klan directed attention almost exclusively against Catholics, who numbered about 8% of the population. In 1922, the Masonic Grand Lodge of Oregon sponsored a bill to require all school-age children to attend public schools. With support of the Klan and Democrat Governor Walter M. Pierce, endorsed by the Klan, the Compulsory Education Law was passed with a majority of votes. Its primary purpose was to shut down Catholic schools in Oregon, but it also affected other private and military schools. It was challenged in court and struck down by the United States Supreme Court Pierce v. Society of Sisters (1925) before it went into effect.
One historian contends that the KKK’s "support for Prohibition represented the single most important bond between Klansmen throughout the nation."  Membership in the Klan and other prohibition groups overlapped, and they often coordinated activities.
For example, Edward Young Clarke, a top leader of the Klan, raised funds for both the Klan and the Anti-Saloon League. A man with his own demons, Clarke was indicted in 1923 for violations of the Mann Act.