The Red River is a river in the north-central United States and central Canada. Originating at the confluence of the Bois de Sioux and Otter Tail rivers between the U.S. states of Minnesota and North Dakota, it flows northward through the Red River Valley, forming most of the border of Minnesota and North Dakota and continuing into Manitoba. It empties into Lake Winnipeg, whose waters join the Nelson River and ultimately flow into Hudson Bay.
The Red River is about 885 kilometres long, of which about 635 kilometres are in the United States and about 255 kilometres are in Canada. The river falls 70 metres on its trip to Lake Winnipeg, where it spreads into the vast deltaic wetland known as Netley Marsh. Several urban areas have developed on both sides of the river, including the city of Winnipeg in Canada, as well as the Fargo-Moorhead and Grand Forks–East Grand Forks metropolitan areas, both of which straddle the North Dakota–Minnesota border. Long an important highway for trade, the Red River has been designated a Canadian Heritage River.