Yellowstone River
 The Yellowstone River (Assiniboine: ȟeȟága wakpá įǧų́ǧa wakpá į́yąǧi wákpa ) is a tributary of the Missouri River approximately 692 miles (1114 km) long in the western United States. Considered the principal tributary of the upper Missouri the river and its tributaries drain a wide area stretching from the Rocky Mountains in the vicinity of the Yellowstone National Park across the mountains and high plains of southern Montana and northern Wyoming.