In the early 20th century, the Klan burned crosses on hillsides or as a means of intimidating people they saw as targets.
The first incarnation of the Ku Klux Klan that formed following the end of the American Civil War did not burn crosses. The belief that reconstruction Klans burned crosses was introduced by Thomas Dixon Jr., in his novel, The Clansman: A Historical Romance of the Ku Klux Klan (1905). A cross burning is first described in Book IV Chapter 2 "The Fiery Cross" on pages 324–326 of the 1905 edition. It is introduced by one of the characters as "the old Scottish rite of the burning cross. It will send a thrill of inspiration to every clansmen in the hills."
In D.W. Griffith's film The Birth of a Nation (1915), an adaptation of Thomas Dixon's novel, two sequences depict cross-burnings. The first sequence depicts a Confederate colonel's little sister, who rejects a marriage proposal by a black captain (of the occupying Union force) and then he must flee after he chases her (the Piedmont, South Carolina legislature had legalized interracial marriages, and the story imagines the social chaos that whites feared would develop). She is cornered at the edge of a cliff and threatens to jump off the cliff unless he stops. He continues his pursuit, and she jumps. Her brother finds her dying at the bottom of the cliff and holds her in his arms; she identifies her attacker before she passes away. The few members of the local clan burn a small (around 8 inches [20 cm]) cross, drenched in the young girl's blood. A kangaroo court is convened, hears the girl's dying words when the colonel gives his testimony, finds the captain guilty of murder, and executes him. The clan members place his body on the front porch of the South Carolina governor's mansion with a square piece of white sheeting with the initials KKK.
The second sequence depicts the aftermath of two home invasions. The first home invasion occurs at the governor's mansion. A black member of the South Carolina legislature proposes marriage to the governor's daughter and, when she rejects his proposal, he threatens her with weapons. The governor attempts to intervene but his attempt fails and he is taken captive. The second home invasion occurs at the house of the Confederate colonel; his mother was revealed to be a clan sympathizer and she expressed her sympathy for the clan by making clan uniforms. The clan wishes to intervene in these hostage situations but it is prevented from doing so by the occupying Union troops. The colonel requests help by burning a cross in the daytime; the black smoke which is produced by the burning cross signals clans from neighboring counties to come to their aid and contest the Union military's control of the town. Each clan wears distinct head-dresses and robes. They greet each other with their faces uncovered although they ride into town with sheeting over their faces. The colonel's uniform has two adjacent square crosses on his robe, presumably from the original clan in Scotland.
In the United States, the first recorded cross burning occurred on November 25, 1915, ten months after the debut of The Birth of a Nation, when a group of men which led by William J. Simmons burned a cross atop Stone Mountain, Georgia, inaugurating the revival of the Ku Klux Klan. The event was attended by 15 charter members and a few aging former members of the original Klan.
Crosses were burned during the Tallahassee bus boycott of 1956.
According to journalist and civil rights advocate Carey McWilliams, in California during the '30s, several crosses were burned as part of the intimidation practices of the vigilante groups which were organized to break off pickers' strikes by the Associated Farmers.