Name one of the two longest rivers in the United States.

The Missouri River is one of the two longest rivers in the United States, with a length of about 2,341 miles. While the Mississippi River is also a contender for the title of the longest river, the Missouri River is often recognized as the longest when measured from its source to its confluence with the Mississippi. This distinction is important in understanding the geography and hydrology of the U.S. river systems. Both rivers play a significant role in the ecosystem and history of the regions they traverse, but the Missouri's length gives it prominence in discussions about the nation's waterways.