The Missouri River is the longest river in North America, traveling roughly 2,341 miles from the Rocky Mountains of western Montana to its confluence with the Mississippi River near St. Louis, Missouri. Crossing plains, badlands, and broad valleys, the river links a vast interior watershed to the continent’s larger river network.
The Missouri begins as snowmelt and mountain springs that gather into swift headwater streams. As it descends from high country to open prairie, the river slows, meanders, and picks up sediment. For thousands of years, this shifting channel built sandbars and side channels that provided habitat for fish and birds and created fertile bottoms for plants to take root.
Indigenous nations—including the Mandan, Hidatsa, Arikara, Lakota, and others—have long relied on the river for food, trade, and travel. In the early 1800s, the Lewis and Clark expedition followed the Missouri upstream, mapping routes and recording species as the United States sought to understand the newly acquired lands of the West. Their journals described a waterway both challenging and essential.
In the twentieth century, large dams and reservoirs were constructed along the upper Missouri and its tributaries. These projects provide hydroelectric power, irrigation water, navigation support, and flood control for downstream communities. Yet the same structures trap sediment, alter seasonal flows, and change water temperatures, which can affect native species such as pallid sturgeon and least terns.
Today, the Missouri River remains a working river and an ecological corridor. Barges move goods on managed stretches, while anglers and bird-watchers seek out quieter backwaters. Engineers, tribal leaders, farmers, and conservationists continue to debate how best to balance navigation, energy, agriculture, cultural resources, and habitat restoration along this dynamic system.
1. Approximately how long is the Missouri River?
2. Where does the Missouri River meet the Mississippi River?
3. Which sequence best describes the river’s change from source to plains?
4. Which Indigenous nations are mentioned as connected to the Missouri River?
5. Which development in the 1900s most changed the river’s natural flow and sediment?
6. According to the passage, which are examples of competing priorities on the Missouri?
7. Which statement best captures the author’s view of the Missouri River today?