Jump to another county SIZE 1,805 mi² FOUNDED 1913 COUNTY SEAT COLUMBUS POPULATION 9,642 LARGEST CITY COLUMBUS COUNTY NUMBER 32 County Fun Fact Cattle, sheep, alfalfa and grass hay are some of the biggest operations and crops in Stillwater County. SENATORLAWMAKER FOR THIS COUNTY Sen. Forrest Mandeville, SD-28 REPRESENTATIVELAWMAKER FOR THIS COUNTY Rep. Fiona Nave, HD-56