Yellowstone River

Yellowstone River, river flowing 671 mi (1,080 km) from northwestern Wyoming north and east through Montana to join the Missouri River at the North Dakota state line. It rises in the Rocky Mountains, flowing into Yellowstone Lake in Yellowstone National Park, emptying by a dramatic drop of over 420 ft (128 m) into Yellowstone Canyon. It then flows northeast through the Great Plains of Montana. The river system, including the tributaries Bighorn, Tongue, and Powder, drains 70,000 sq mi (181,000 sq km). The river is visited for its natural beauty and is used for irrigation.