What is the longest river in the United States?

The Missouri River is recognized as the longest river in the United States, stretching approximately 2,341 miles from its source in Montana to its confluence with the Mississippi River in St. Louis, Missouri. This river plays a significant role in the geography and history of the country, serving as a vital waterway for transportation, commerce, and agriculture.

In comparison, while the Mississippi River is often thought of as one of the most significant rivers in the U.S. due to its length and historical importance, it is actually shorter than the Missouri River when measured in total length. The Rio Grande and the Colorado River, while noteworthy for other reasons—such as the natural borders they create and the ecosystems they support—do not surpass the Missouri River in length.

Understanding the distinction in river lengths highlights the importance of accurate geographical knowledge in civics, especially as it pertains to context about natural resources and regional development within the United States.