Missouri River

The Missouri River is the longest river in the United States at 2,540 miles long. Together with the Mississippi River, it forms the fourth largest river system in the world. It begins in Western Montana and flows to the Mississippi River just north of St. Louis. It travels through several states including Montana, North Dakota, South Dakota, Iowa, Nebraska, Kansas, and Missouri.



The first explorers to travel the entire length of the Missouri River were Lewis and Clark. They used the Missouri to make their way west when exploring the Louisiana Purchase. The river played an important role in the early history of the American frontier as the major trails to the west, such as the Oregon and Santa Fe Trail, began at the Missouri River.