What Is the Longest River in North America?

The Mississippi River is the longest river in North America at 3,734 km (2,320 miles) from its source at Lake Itasca, Minnesota to the Gulf of Mexico.

Key Facts:

• Drainage Basin: 3.2 million km² (1.24 million mi²) — 41% of contiguous US; 3rd largest globally.
• Major Tributaries: Missouri (longest tributary, 3,767 km from source), Ohio (largest by volume), Arkansas, Tennessee, Illinois, Red River.
• Economic Role: Historic trade artery; modern barge traffic moves 500M+ tons/year (grain, coal, chemicals, petroleum).
• Ecology: 260+ fish species, 40% of US migratory waterfowl flyway, vast floodplain wetlands (now 90% lost).
• Management: Levees, locks, dams, channelization by USACE; ongoing restoration efforts.

Note: The Missouri River is longer from its ultimate source (Brower's Spring, MT) to the Mississippi confluence (3,767 km vs. Mississippi's 3,734 km to Gulf), but by convention the Mississippi is the main stem.