Yankton County administrative offices are located at 321 West 3rd Street, Yankton, SD 57078; phone: 605-260-4400.
Yankton County is located along the southeastern border of South Dakota, separated from the State of Nebraska by the Missouri River. The physical area comprises 519 square miles of land. The county is named for the Yankton band of the Sioux Indians. Joseph R. Hanson is credited as being the first settler in 1859. [http://www.co.yankton.sd.us, accessed October, 2013.]