Historic route in the US states of Wyoming and Montana. It was developed in 1862–63 by John Bozeman as an approach to the goldfields of southwest Montana that did not necessitate an arduous crossing of the Rocky Mountains or a long journey upstream on the Missouri River. Because it infringed on the lands of the Sioux, it soon became the scene of many violent clashes between American Indians and White prospectors and troops. It was abandoned as a viable route by 1868.
Starting in the vicinity of modern Douglas, in eastern Wyoming, on the interstate route I-25, the Bozeman Trail first ran northwest across the edge of the Missouri Plateau before crossing the upper Powder River and proceeding along the east of the Bighorn Mountains. It entered Montana near modern Decker, crossed the Bighorn River, and finally ran west along the Yellowstone River valley.
A number of famous forts and battle sites are situated on the Bozeman Trail. They include Fort Reno, 8 mi/13 km north-northeast of Sussex, Wyoming, on the Powder River; Fort Phil Kearny, 2 mi/3 km southeast of Story, Wyoming, and just west of I-90/87, on Little Piney Creek; and Fort C F Smith, which was within what is now the Bighorn Canyon National Recreation Area, in Montana. Near Fort Phil Kearny is the site (just north-northwest) of the 1866 Fetterman Massacre, in which a company of troops were annihilated. Near Story, northwest of the fort, is the site of the 1867 Wagon Box Fight, in which a small group of troops inflicted heavy losses on attacking Sioux. At Ranchester, on I-90, is the Connor Battlefield, site of an 1865 battle in which troops killed dozens of Indian men, women, and children. When the forts were abandoned, the Sioux destroyed them, but historical markers have been placed at all sites.