What is the longest river in the United States?

The longest river in the United States is the Missouri River. Flowing for approximately 2,341 miles (3,766 kilometers), the Missouri River is a tributary of the Mississippi River and stretches across seven states, from Montana to Missouri. The river played a key role in the exploration and settlement of the American West, serving as an important waterway for trade and transportation. It passes through a variety of landscapes, including plains, forests, and cities, and remains a vital water resource for agriculture and industry.