The original Ku Klux Klan was organized by ex-Confederate elements to oppose the Reconstruction policies of the radical Republican Congress and to maintain white supremacy. After the Civil War, when local government in the South was weak or nonexistent and there were fears of black outrages and even of an insurrection, informal vigilante organizations or armed patrols were formed in almost all communities. These were linked together in societies, such as the Men of Justice, the Pale Faces, the Constitutional Union Guards, the White Brotherhood, and the Order of the White Rose. The Ku Klux Klan was the best known of these, and in time it absorbed many of the smaller organizations.

It was organized at Pulaski, Tenn., in May, 1866. Its strange disguises, its silent parades, its midnight rides, its mysterious language and commands, were found to be most effective in playing upon fears and superstitions. The riders muffled their horses' feet and covered the horses with white robes. They themselves, dressed in flowing white sheets, their faces covered with white masks, and with skulls at their saddle horns, posed as spirits of the Confederate dead returned from the battlefields. Although the Klan was often able to achieve its aims by terror alone, whippings and lynchings were also used, not only against blacks but also against the so-called carpetbaggers and scalawags.

A general organization of the local Klans was effected in Apr., 1867, at Nashville, Tenn. Gen. N. B. Forrest, the famous Confederate cavalry leader, was made Grand Wizard of the Empire and was assisted by ten Genii. Each state constituted a Realm under a Grand Dragon with eight Hydras as a staff; several counties formed a Dominion controlled by a Grand Titan and six Furies; a county was a Province ruled by a Grand Giant and four Night Hawks; the local Den was governed by a Grand Cyclops with two Night Hawks as aides. The individual members were called Ghouls.

Control over local Dens was not as complete as this organization would seem to indicate, and reckless and even lawless local leaders sometimes committed acts that the leaders could not countenance. General Forrest, in Jan., 1869, seemingly under some apprehension as to the use of its power, ordered the disbandment of the Klan and resigned as Grand Wizard. Local organizations continued, some of them for many years.

The Klan was particularly effective in systematically keeping black men away from the polls, so that the ex-Confederates gained political control in many states. Congress in 1870 and 1871 passed legislation to combat the Klan (see force bill). The Klan was especially strong in the mountain and Piedmont areas. In the Lower South the Knights of the White Camelia were dominant. That order, founded (1867) in Louisiana, is reputed to have had even more members than the Ku Klux Klan, but its membership was more conservative and its actions less spectacular. It had a similar divisional organization, with headquarters in New Orleans.

The second Ku Klux Klan was founded in 1915 by William J. Simmons, an ex-minister and promoter of fraternal orders; its first meeting was held on Stone Mt., Ga. The new Klan had a wider program than its forerunner, for it added to white supremacy an intense nativism and anti-Catholicism (it was also anti-Semitic) closely related to that of the Know-Nothing movement of the middle 19th cent. Consequently its appeal was not sectional, and, aided after 1920 by the activities of professional promoters Elizabeth Tyler and Edward Y. Clarke, it spread rapidly throughout the North as well as the South. It furnished an outlet for the militant patriotism aroused by World War I, and it stressed fundamentalism in religion.

Professing itself nonpolitical, the Klan nevertheless controlled politics in many communities and in 1922, 1924, and 1926 elected many state officials and a number of Congressmen. Texas, Oklahoma, Indiana, Oregon, and Maine were particularly under its influence. Its power in the Midwest was broken during the late 1920s when David C. Stephenson, a major Klan leader there, was convicted of second-degree murder, and evidence of corruption came out that led to the indictment of the governor of Indiana and the mayor of Indianapolis, both supporters of the Klan. The Klan frequently took extralegal measures, especially against those whom it considered its enemies. As was the case with the earlier Klan, some of these measures, whether authorized by the central organization or not, were extreme.

At its peak in the mid-1920s its membership was estimated at 4 million to 5 million. Although the actual figures were probably much smaller, the Klan nevertheless declined with amazing rapidity to an estimated 30,000 by 1930. The Klan spirit, however, was a factor in breaking the Democratic hold on the South in 1928, when Alfred E. Smith, a Roman Catholic, was that party's presidential candidate. Its collapse thereafter was largely due to state laws that forbade masks and eliminated the secret element, to the bad publicity the organization received through its thugs and swindlers, and apparently from the declining interest of the members. With the depression of the 1930s, dues-paying membership of the Klan shrank to almost nothing. Meanwhile, many of its leaders had done extremely well financially from the dues and the sale of Klan paraphernalia.

After World War II, Dr. Samuel Green of Georgia led a concerted attempt to revive the Klan, but it failed dismally as the organization splintered and as state after state specifically barred the order. Southern civil-rights activities during the 1960s gave the Klan a new impetus and led to revivals of scattered Klan organizations. The most notable of these were Mississippi's White Knights of the Ku Klux Klan, led by Robert Shelton. The newly revived Klan groups were responsible for violent attacks against blacks and civil-rights workers in cities throughout the South, including Jacksonville and St. Augustine, Fla., Birmingham and Montgomery, Ala., and Meridian, Miss. In spite of its efforts, the new Klan was not strong, and by the end of the decade its power and membership had declined to practically nothing. Although a resurgence of support for the Klan was manifest in the surprising popularity in the early 1990s of David Duke of Louisiana, actual membership in Klan organizations is estimated to be in the low thousands.