Bighorn River Wind River Canyon near the town of Thermopolis. From there, the river flows through the Bighorn Basin in north central Wyoming, passing through Thermopolis and Hot Springs State Park. At the border with Montana, the river turns northeast, and flows past the north end of the Bighorn Mountains, through the Crow Indian Reservation, where the Yellowtail Dam forms the Bighorn Lake reservoir. The reservoir and the surrounding canyon are part of the Bighorn Canyon National Recreation Area. The Little Bighorn River joins the Bighorn near the town of Hardin, Montana. Approximately fifty miles farther downriver, the Bighorn River ends where
Battle of the Little Bighorn Sitting Bull's ranks for the summer buffalo hunt. The agents did not take into account the many thousands of these "reservation Indians" who had unofficially left the reservation to join their "uncooperative non-reservation cousins led by Sitting Bull". Thus, Custer unknowingly faced thousands of Indians, including the 800 non-reservation "hostiles". All Army plans were based on the incorrect numbers. Although Custer was severely criticized after the battle for not having accepted reinforcements and for dividing his forces, it must be understood that he had accepted the same official government estimates of hostiles in the area which Terry and Gibbon had