Big Horn is an unincorporated community and census-designated place in Sheridan County, Wyoming, United States. The population was 457 at the 2020 census. Big Horn is along the valley of Little Goose Creek. From 1866 to 1868, the military cutoff route of the Bozeman Trail crossed Little Goose Creek, where Big Horn was later located. The trail was used b…Big Horn is an unincorporated community and census-designated place in Sheridan County, Wyoming, United States. The population was 457 at the 2020 census. Big Horn is along the valley of Little Goose Creek. From 1866 to 1868, the military cutoff route of the Bozeman Trail crossed Little Goose Creek, where Big Horn was later located. The trail was used by travelers going to gold fields in Montana, but was plagued by Lakota attacks under Red Cloud. Fort Phil Kearny was established on Piney Creek, but continued harassment by the Lakota led to its abandonment and the withdrawal of the U.S. Army from the Powder River Country under the Fort Laramie Treaty of 1868.