The Ku Klux Klan is formed.

The Ku Klux Klan (), commonly shortened to the KKK or the Klan, is an American white supremacist terrorist and hate group whose primary targets are African Americans, Jews, Latinos, Asian Americans, Catholics, Native Americans as well as immigrants, leftists, homosexuals, Muslims, and atheists.The Klan has existed in three distinct eras. Each has advocated extremist reactionary positions such as white nationalism, anti-immigration and—especially in later iterations—Nordicism, antisemitism, anti-Catholicism, Prohibition, right-wing populism, anti-communism, homophobia, Islamophobia, Anti-Progressivism and anti-atheism. Historically, the first Klan used terrorism—both physical assault and murder—against politically active blacks and their allies in the Southern United States in the late 1860s. All three movements have called for the "purification" of American society, and are all considered right-wing extremist organizations. In each era, membership was secret and estimates of the total were highly exaggerated by both friends and enemies.

The first Klan was established in the wake of the American Civil War and was a defining organization of the Reconstruction era. Organized in numerous chapters across the Southern United States, it was suppressed through federal law enforcement around 1871. It sought to overthrow the Republican state governments in the South, especially by using voter intimidation and targeted violence against African-American leaders. Each chapter was autonomous and highly secret as to membership and plans. Members made their own, often colorful, costumes: robes, masks and conical hats, designed to be terrifying and to hide their identities.The second Klan started small in Georgia in 1915. It grew after 1920 and flourished nationwide in the early and mid-1920s, including urban areas of the Midwest and West. Taking inspiration from D. W. Griffith's 1915 silent film The Birth of a Nation, which mythologized the founding of the first Klan, it employed marketing techniques and a popular fraternal organization structure. Rooted in local Protestant communities, it sought to maintain white supremacy, often took a pro-Prohibition and pro-compulsory public education stance, and it opposed Jews, while also stressing its opposition to the alleged political power of the pope and the Catholic Church. This second Klan flourished both in the south and northern states; it was funded by initiation fees and selling its members a standard white costume. The chapters did not have dues. It used K-words which were similar to those used by the first Klan, while adding cross burnings and mass parades to intimidate others. It rapidly declined in the later half of the 1920s.

The third and current manifestation of the KKK emerged after 1950, in the form of localized and isolated groups that use the KKK name. They have focused on opposition to the civil rights movement, often using violence and murder to suppress activists. This manifestation is classified as a hate group by the Anti-Defamation League and the Southern Poverty Law Center. As of 2016, the Anti-Defamation League puts total KKK membership nationwide at around 3,000, while the Southern Poverty Law Center puts it at 6,000 members total.The second and third incarnations of the Ku Klux Klan made frequent references to a false mythologized perception of America's "Anglo-Saxon" blood, hearkening back to 19th-century nativism. Although members of the KKK swear to uphold Christian morality, the group is widely denounced by Christian denominations.