The valley was long an area of habitation by various indigenous cultures, including the historic Ojibwe and Métis peoples. The river flows north through a wide ancient lake plain to Lake Winnipeg. The geography and seasonal conditions can produce devastating floods, with several recorded since the mid-20th century.

"The Red River Valley" therefore is an unfortunate misnomer for this landscape. It is not a valley in the sense that it was formed by a river. Instead, the origins of this flat plain lie as the floor of what was an enormous glacial lake. The actual "valley" of the Red River is only a few hundred feet wide at Fargo.

The soil is very deep. The alluvial soil depth at Grand Forks, including topsoil, loam and clay, is “fifty to seventy-five feet deep,” and under that lies cretaceous shale 300-feet thick – over granite or gneiss bedrock.