What is the longest river in the United States?

The Missouri River is the longest river in the United States at 2,341 miles long. The Mississippi River is the second longest, at 2,340 miles long. The longest rivers in the world include the Nile River at 4,132 miles long, the Amazon at 4,000 miles long and the Yangtze at 3,915 miles long.

The Missouri River was named after the Missouri Native American Tribe and flows through Bismark, North Dakota; Pierre, South Dakota; Omaha, Nebraska; Kansas City, Missouri; and St. Louis, Missouri. The river is often referred to as the "Big Muddy" because the river has relocated approximately 2,000 feet of dirt in the 200 years Americans have lived near the river.