| Marmaton River | |
| Map: | Osagerivermap.png |
| Subdivision Type1: | Country |
| Subdivision Name1: | United States |
| Subdivision Type2: | State |
| Subdivision Name2: | Kansas, Missouri |
| Length: | 102miles |
| Discharge1 Location: | USGS 06918060 near Nevada, MO[1] |
| Discharge1 Min: | 0.03cuft/s |
| Discharge1 Avg: | 1051cuft/s |
| Discharge1 Max: | 33800cuft/s |
| Source1 Location: | Allen County, Kansas |
| Source1 Coordinates: | 37.9458°N -95.1308°W |
| Source1 Elevation: | 1105feet |
| Mouth: | Little Osage River |
| Mouth Location: | Vernon County, Missouri |
| Mouth Coordinates: | 37.9992°N -94.3189°W |
| Mouth Elevation: | 732feet |
| Custom Label: | Watersheds |
| Custom Data: | Marmaton-Little Osage-Osage-Missouri-Mississippi |
The Marmaton River (MAR-muh-tuhn) is a 102adj=midNaNadj=mid[2] tributary of the Little Osage River in southeastern Kansas and western Missouri in the United States. Via the Little Osage, Osage and Missouri rivers, it is part of the watershed of the Mississippi River.
The Marmaton River rises in Kansas northeast of Moran in eastern Allen County and flows generally eastward through Bourbon County in Kansas and Vernon County in Missouri, past the towns of Uniontown, Redfield and Fort Scott in Kansas and Deerfield in Missouri. It joins the Little Osage River from the south, 7miles south-southeast of Rich Hill, Missouri.
Marmaton is a corruption of Marmiton, a French name given by fur traders meaning "scullion".[3]