Bad Pass Trail, also called the Sioux Trail, runs along the western side of Bighorn Canyon on the present-day Wyoming-Montana border. Established by Native Americans in pre-Columbian times, it linked the Bighorn Basin with bison-hunting grounds near Grapevine Creek and may have been used for ten to twelve thousand years. Its most notable remains are about three hundred stone cairns, likely enlarged over time by travelers leaving stones for good luck, along with as many as one thousand nearby tipi rings. After 1824, fur trappers and mountain men also used the route to bypass Bighorn Canyon and connect overland travel with river shipment toward St. Louis.