Sioux National Forest was established in Montana and South Dakota on July 1, 1908 with 249,653 acres (1,010.31 km2) from the consolidation of Cave Hills, Ekalaka, Long Pine, Short Pine and Slim Buttes National Forests. On January 13, 1920 the entire forest was absorbed by Custer National Forest and the name preserved as the Sioux District of Custer National Forest.[1][2]