The James River (also known as the Jim River or the Dakota River) is a tributary of the Missouri River, approximately 710 mi (1,143 km) long, in the U.S. states of North Dakota and South Dakota. The river provides the main drainage of the flat lowland area of the Dakotas between the two plateau regions known as the Coteau du Missouri and the Coteau des Prairies. This narrow area was formed by the lobe of a glacier during the last ice age, and as a consequence the watershed of the river is slender and it has few major tributaries for a river of its length. The James River has the somewhat dubious distinction of being the longest unnavigable river in the world.
The river rises in Wells County, North Dakota, approximately 10 mi (16 km) northwest of Fessenden. It flows briefly east towards New Rockford, then generally SSE through eastern North Dakota, past Jamestown, where it is first impounded by a large reservoir (the Jamestown Dam), and then joined by the Pipestem River. It enters northeastern South Dakota in Brown County, where it is impounded to form two reservoirs northeast of Aberdeen.
At Columbia, it is joined by the Elm River. Flowing southward across eastern South Dakota, it passes Huron and Mitchell, where it is joined by the Firesteel Creek. South of Mitchell, it flows southeast and joins the Missouri just east of Yankton.
Originally called "E-ta-zi-po-ka-se Wakpa," literally "unnavigable river" by the Dakota tribes, the river was named Rivière aux Jacques (literally, "James River" in English) by French explorers. By the time Dakota Territory was incorporated, it was being called the James River. This name was provided by Thomas L. Rosser, a former Confederate general who helped to build the Northern Pacific Railroad across North Dakota. A true Virginian, he named the river and the settlement of Jamestown, North Dakota, after the English colony of Jamestown, Virginia. (The coincidence of the old French name "Jacques" directly translating as "James" in English is noted.) However, the Organic Act of 1861 that formed the territory renamed it the Dakota River. Apparently this did not catch on, as the river retains its pre-1861 name.