The Red River of the North is a large, meandering river that flows northwards from South Dakota's Lake Traverse into Manitoba's Lake Winnipeg. Along the way, it forms the border between North Dakota and Minnesota. The Red River system is the southernmost portion of the Hudson Bay basin.

The Red River of the North should not be confused with its namesake, which flows eastward through north Texas and Oklahoma, and into the Mississippi. The song 'The Red River Valley' refers to that particular river, not the one described below.

Modern Geography
From Lake Traverse to Wahpeton, ND, the Red is known as the Bois de Sioux. At Wahpeton, the Bois de Sioux converges with the Ottertail River, and becomes the Red River proper.

The Red's total length measures over 880 km, but this figure is exaggerated by the serpentine nature of the river's path. The total distance (as the crow flies) from source to mouth is only 456 km. The watershed for the Red River covers about 127,000 km2, and over 290,000 km2 when including all of its tributaries. The Red has a very low gradient (< .00001 in places), resulting in a rather slow-moving current and its meandering riverbed.

The Red River flows through the very aptly-named Red River Valley. The valley predates the river by several thousand years, having been formed through the differential erosion of the bedrock underlying the valley. The western edge of the valley is bounded by the Manitoba Escarpment, a terraced ridge system where the bedrock is largely resistant shale. To the east of the valley are the granites of the Canadian Shield. The valley itself is underlain by relatively soft Ordovician limestone, which was gouged out during a glacial advance approximately 20,000 years ago. The result was a wide (over 75 km in places), shallow valley.

Several large communities sit astride the river's banks: Wahpeton, North Dakota; Fargo, North Dakota; Moorhead, Minnesota; Grand Forks, North Dakota; East Grand Forks, Minnesota; Winnipeg, Manitoba and Selkirk, Manitoba.

The Red is fed by several large tributaries, including the Assiniboine River, the Sheyenne River and the Pembina River. The Assiniboine is a major east-west waterway, reaching to southwest Saskatchewan. The Red and the Assiniboine meet at The Forks in Winnipeg; an area that has been a traditional meeting place for the area's inhabitants for millennia, and is now a National Historic Site and popular tourist attraction. The Sheyenne flows eastward though central North Dakota, joining the Red just north of Fargo-Moorhead. The Pembina River skirts the Manitoba/North Dakota border, meeting the Red at Pembina, North Dakota.

History
The Red is a relatively young river, only having flowed for approximately 8,000 years. As the waters of ancient Lake Agassiz receeded (following the failure of glacial ice dams and the sudden outflow of water into the St. Lawrence basin), the Red River Valley provided a natural channel for drainage into the shrinking Agassiz basin. Eventually Lake Agassiz disappeared, leaving several smaller lakes in its place, and the nascent Red began flowing into the largest of these newer lakes, Lake Winnipeg.

The new river was soon exploited by various Plains Indians tribes who migrated into the area. The Red soon became a link in an informal trade network that linked the northern plains with First Nations residing along the Mississippi River. With the arrival of Europeans in the area, the Red and its tributaries were used by trappers, coureurs de bois and voyageurs in the ever-expaning fur trade. Until the railroads arrived in the late 19th Century, the most reliable forms of summertime transport were rivercraft: canoes, York boats and barges.

Floods
Aside from providing a navigable waterway (for small craft, at least), the Red River Valley turned out to be prime agricultural land. Every spring, meltwater causes the river to swell, often spilling over its banks and spreading alluvial silt throughout the valley. From time to time, the same spring flooding that replenishes the topsoil, drowns the entire valley in murky floodwater .

Several major floods have hit the area during recorded history. The highest recorded water levels hit the area in 1826, nearly wiping out the Red River Settlement; peak levels from that flood are the literal watermark to which subsequent floods have been compared. Less significant, but still disastrous, floods followed in 1852 and 1861. After this, the valley gained some measure of respite until 1950. That year, a major flood hit the area north of the Canadian border, forcing the evacuation of over 100,000 Winnipeg-area residents.

Following the 1950 flood, Winnipeg's Red River Floodway was constructed to prevent a repeat of the damage caused by a flood of comparable intensity. The floodway consisted of a 47 km long diversion channel skirting the eastern edge of the city, with a lock system controlling flow into the floodway. The floodway was tested by serious floods in 1979 and 1997, the latter of which exceeded the levels of the 1950 flood, and all but wiped out Grand Forks. Winnipeg survived with only minor damage, even though it lay at the most vulnerable area in the floodplain.


Sources
Manitoba Conservation, Water Branch Index Page - http://www.gov.mb.ca/natres/watres/index.html
Natural Resources Canada, Red River - http://sts.gsc.nrcan.gc.ca/hydro/redriver/index.asp