Why does the Red River flow north?
Lake Agassiz, a lake formed by melting glaciers, covered much of what is today western Minnesota, eastern North Dakota, southern Manitoba, and southwestern Ontario from about 12,500 years ago to about 7,500 years ago. Lake Agassiz virtually disappeared, leaving a few remnants like Minnesota’s Upper and Lower Red Lakes and Lake of the Woods and Canada’s Lake Winnipeg, Lake Manitoba, and Lake Winnipegosis. Lake Agassiz also left a fertile, flat plain that drains to the north, ultimately to Hudson Bay. The Red River flows north through this plain to Lake Winnipeg because, despite the plain being very flat, a difference in elevation exists along the route of the river, making the line between southeastern North Dakota and Lake Winnipeg slightly downhill. At the confluence of the Bois de Sioux and Otter Tail Rivers near Wahpeton, North Dakota, where the Red River begins, the elevation is 943 feet above mean sea level. The elevation of Lake Winnipeg is 714 feet above mean sea level. This web
