Founded in 1866, the Ku Klux Klan (KKK) extended into almost every southern state by 1870 and became a vehicle for white southern resistance to the Republican Party's Reconstruction-era policies aimed at establishing political and economic equality for blacks. Its members waged an underground campaign of intimidation and violence directed at white and black Republican leaders. Though Congress passed legislation designed to curb Klan terrorism, the organization saw its primary goal–the reestablishment of white supremacy–fulfilled through Democratic victories in state legislatures across the South in the 1870s. http://www.history.com/topics/ku-klux-klan
It actually started out as sort of a joke...like a fun little elite society. But then it turned pretty ugly. You can do some research about them in your local library. Also, the history channel has a couple of documentaries on them that you can check out through their site.