Marmaton River  The Marmaton River ("MAR-muh-tuhn") is a  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, south-southeast of Rich Hill, Missouri. Marmaton is a corruption of "Marmiton", a French name given by fur traders meaning "scullion".