Prelims ask
Bird-foot delta, Gulf of Mexico, Missouri longer, Ohio wetter, Itasca.
North America
Mississippi–Missouri
The combined system is the usual ‘fourth longest’ on textbook lists. Quote the system, not the upper Mississippi, when length is asked.
- Source
- Mississippi proper: Lake Itasca, Minnesota. Missouri: Rockies of Montana (Jefferson, Madison and Gallatin).
- Countries
- United States. A small part of the Missouri basin reaches Canada.
- Direction
- South.
- Mouth
- Gulf of Mexico.
- Length
- About 6,275 km for the Missouri–Mississippi system. The Mississippi alone is much shorter.
- Major tributaries
- Missouri, Ohio, Arkansas, Red. The Ohio contributes more water than the Missouri.
- Delta or estuary
- Bird-foot delta.
- Basin
- Largest drainage basin in North America.
- One exam fact
- Two truths at once: the Missouri is the longer stem; the Ohio is the wetter stem.
Mains use
Use when explaining why ‘the source’ and ‘the main discharge’ need not be the same headstream.