Sioux pass of the three rivers, Missouri River, United States (Google Maps ⧉, OpenStreetMap ⧉)
Referenced In
History of the Expedition under the Command of Captains Lewis and Clark / To the Sources of the Missouri, Thence Across the Rocky Mountains and Down the River Columbia to the Pacific Ocean
by Meriwether Lewis, William Clark"And as the Sioux generally cross the Missouri at this place, it is called the Sioux pass of the three rivers."