Several national wildlife refuges protect important waterfowl habitat on more than 100,000 acres in western North Dakota. Navigable rivers in the region include the Missouri River and its tributaries, the Little Missouri, Cannonball and Knife Heart. The Missouri marks the beginning of The West, with its heritage of Indian tribes, cattle drives, settlers and shoot-outs, and its legacy of powerful personalities: George Armstrong Custer, Sitting Bull, Lewis and Clark, Sakakawea, Theodore Roosevelt and other fabled figures.