What is the longest river in North America?
The longest river is the Mississippi River, and the longest
combination is the Mississippi-Missouri River. The Missouri crosses
the central US before joining the Mississippi at St Louis.
The Mississippi itself from Minnesota to the Gulf of Mexico is
3779 km (2348 miles) long.
The entire Mississippi-Missouri combination, measured from
Brower's Creek in Montana to the Gulf, is a continuous waterway
more than 6027 km (3745 miles) in length.