Little Bighorn River Canyon in Wyoming, the Little Bighorn receives other mountain streams as tributaries including the Dry Fork (which despite its name maintains a permanent, year-round significant flow of water into the Little Bighorn), and the West Fork of the Little Bighorn. After issuing from its canyon at the Montana-Wyoming line the Little Bighorn flows northward across the Crow Indian Reservation. The river flows past the towns of Wyola, Lodge Grass and Crow Agency, and joins the Bighorn River near the town of Hardin. At Wyola, Montana, the Little Bighorn receives the flow of Pass Creek flowing north from the Bighorn Mountains.
Desert bighorn sheep establish two desert areas in southwestern Arizona to help preserve the desert bighorn sheep: Cabeza Prieta National Wildlife Refuge and the Kofa National Wildlife Refuge. In 1941, the San Andres National Wildlife Refuge in New Mexico was added. Desert bighorn sheep populations have trended upward since the 1960s when their population was estimated at 6,700-8,100. The upward trend was caused by conservation measures, including habitat preservation. In 1980, desert bighorn sheep populations were estimated at 8,415-9,040. A state-by-state survey was conducted a few years later and estimated the overall US desert bighorn sheep population at 15,980. The 1993 estimate of