Richland county is the southeasternmost of North Dakota's counties and calls Wahpeton its county seat. The county population on July 1, 1999, was 17,924, a decrease of 224 over the 1990 census.
The Boise de Sioux River forms the southern half of the eastern border of the county while the Ottertail River joins the former at Wahpeton to form the headwaters of the Red River of the North which then flows north and becomes the county's border with Minnesota. In addition to these three rivers, the Wild Rice River enters the county in the southwest corner flowing first to the northeast, then to the southeast and finally north paralleling the Red R. of the North.
