The 10 Longest Rivers in the US: Flow and Hydrology

The United States contains some of the largest river systems in the world. Here are the ten longest US rivers by length, along with their typical flow characteristics as recorded by USGS.

1. Missouri River (2,341 miles): The longest US river drains 529,000 square miles from Montana to St. Louis. Average discharge at the mouth: ~55,000 CFS. Spring snowmelt drives dramatic peaks.
2. Mississippi River (2,340 miles): The largest river by watershed area (1.2 million sq mi). Average discharge at the Gulf: ~600,000 CFS. The Old River Control Structure controls the split with the Atchafalaya.
3. Yukon River (1,979 miles in US): Alaska's dominant river system. Average discharge ~225,000 CFS at the mouth. Remote and largely unmonitored.
4. Rio Grande (1,896 miles): Forms the US-Mexico border for 1,254 miles. Heavily regulated; stretches near El Paso run nearly dry in drought years.
5. Arkansas River (1,469 miles): Rises in Colorado's Sawatch Range and flows 1,469 miles to the Mississippi. Flow ranges from 100 CFS near Pueblo to 35,000+ CFS at Little Rock during floods.
6. Colorado River (1,450 miles): The American Southwest's lifeline. Completely allocated — no water reaches the Gulf of California in most years.
7. Snake River (1,078 miles): Major Columbia tributary. Heavily dammed, with discharge varying dramatically based on irrigation demand and dam operations.
8. Ohio River (981 miles): The most commercially important US river. Average discharge exceeds 250,000 CFS near the Mississippi confluence.
9. Red River (1,360 miles): Forms the Oklahoma-Texas border. Highly variable; can be nearly dry or in major flood within weeks of each other.
10. Columbia River (1,243 miles): The most powerful river in North America by discharge. Average discharge at the mouth: ~265,000 CFS.