White caps were groups involved in whitecapping who were operating in southern Indiana in the late 19th century. They engaged in vigilante justice and lynchings and in modern times are often viewed as engaging in terrorism. They became common in the state following the American Civil War and lasted until the turn of the 20th century. White caps were especially active in Crawford and neighboring counties in the late 1880s. Several members of the Reno Gang were lynched in 1868, causing an international incident. Some of the members had been extradited to the United States from Canada and were supposed to be under federal protection. Lynchings continued against other criminals, but when two possibly innocent men were killed in Corydon in 1889, Indiana responded by cracking down on the white cap vigilante groups beginning in the administration of Isaac P. Gray.
Governor of Indiana James A. Mount belonged to one of the white cap groups, and reversed state policy of trying to stop the groups. His successor, Winfield T. Durbin, resumed the policy in 1900, two years after the Indiana General Assembly passed a strong anti-lynching law.