Answer:
The Ku Klux Klan (KKK) was originally an American Protestant "white power" organization founded by Southern State veterans in 1865, but dissolved in 1880. The original KKK counteracted reforms that were imposed on the Southern states in the treatment of former slaves. They focused on terror against black people, other colored people and fighters for constitutional rights, but were also anti-Semitic, homophobic, anti-Islamic, anti-Catholic and anti-communist and turned against new immigrants. The first Ku Klux Klan gained widespread support in the southern states of the US as a white reaction to the abolition of slavery at the end of the Civil War.
A new Ku Klux Klan originated in Atlanta in 1915. The founder was William J. Simmons, and it is this KKK that for years after that became a popular racist organization with approximately four million members at its peak in the 1920s. Its purpose now was to prevent the increase of Catholics, Jews, dark-skinned and other immigrants in the United States. Finally, KKK was disbanded during World War II.
Today, organizations like the paramilitaries patrolling the border with Mexico (the United Constitutional Patriots, for example) carry out intimidation and violence against minorities, in a very similar way to what the KKK used in its time.