The over 700 mile-long James River in South Dakota (also known as the Jim River) is a tributary of the Missouri River, in North Dakota and South Dakota. The James River has the less than desirable distinction of being the longest unnavigable river in the world. It is born in Wells County, North Dakota, where it flows through eastern North Dakota. The river is 1st impounded by the Jamestown Dam reservoir, and then joined by the Pipestem River. It enters northeastern South Dakota in Brown County, where it is impounded to form two reservoirs lakes near Aberdeen.

The Dakota Indians called the river "E-ta-zi-po-ka-se Wakpa," which literally means "unnavigable river". French explorers called it Rivière aux Jacques by French explorers, but by the time Dakota Territory was incorporated Anglophones had changed the name to the “James River” in honor of Jamestown, North Dakota, itself named after the English colony of Jamestown, Virginia.