Human: With regards to the Mississippi River, what is the longest river in the United States? Assistant: 
The Mississippi River is the longest river in the United States, with a length of 2,341 miles. The Mississippi River is also the largest river in North America, flowing through nine U.S. states and two Canadian provinces. The river drains a drainage basin of 1,349,000 square miles (3,660,000 km2), and its watershed drains an area of 2,370,000 square miles (6,200,000 km2).