Lat/Long: 38.8167, -90.1833
Formed by confluence of Jefferson, Madison, and Gallatin rivers in Gallatin County, Montana. The river flows east and southeast for 2,683 miles before joining the Mississippi River approximately ten miles north of St. Louis. The Missouri River flows through Montana, North Dakota, South Dakota, Nebraska, Iowa, Kansas and Missouri. The river is navigable during high water with flat-bottom boats and was explored by the French traders & later by Lewis and Clark in 1804-1806.
Webster's New Geographical Dictionary (Springfield, MA: Merriam-Webster, 1988), 773.