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.

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. Because of the low gradient of the Red and the young age of the river, the "valley" is not fully mature.

The soils in the Red River valley developed under the natural vegetation of the tall grass prairie. The soil at this site is a Bearden silty clay loam. The Bearden soil series is somewhat poorly drained, dark colored, medium textured soil developed from calcareous, lacustrine clay.

The western edge of the Red River Valley is a long ridge of land running north and south. This ridge is so small it is difficult to see in the southern part of the state. In the north, however, the ridge becomes the Pembina Mountains, a heavily wooded area near Walhalla, North Dakota.