Name one of the longest rivers in the United States.

The longest rivers in the United States include the Missouri River and the Mississippi River, both of which are significant contributors to the country's geography and ecology. The Missouri River, stretching about 2,341 miles, is recognized as the longest river in the United States, while the Mississippi River ranks second in length, measuring about 2,340 miles. These rivers play crucial roles in transportation, agriculture, and natural ecosystems.

The Sierra River is not known as one of the longest rivers in the United States; it is actually a smaller river located in California. This helps clarify that while the other two rivers are major waterways with extensive lengths, the Sierra River does not hold that distinction and is less prominent in discussions of the longest rivers in the country.