where is union county
Union County, South Dakota. Union County, created in 1862, organized in 1862, was originally named Cole County for Austin Cole, who was a member of the first Territorial Legislature. Two years later, the boundaries were rearranged and the name changed to Union because of sentiment for the Union side of the civil war. The county seat is located in Elk Point, and it also includes the communities of Alcester, Beresford, Dakota Dunes, Jefferson, & North Sioux City.