S.D. Codified Laws § 8-1-20
Whenever in any civil township, whether such civil township is or is not coextensive in area with a congressional township, containing an area platted, developed, and occupied as a village in which reside more than twenty-five percent of the legal voters of the civil township, in which village legal voters are no less than fifty in number, and which village has a population of not less than one hundred and has not been incorporated as a municipality, sixty percent of the legal voters residing in the portion of the civil township outside the area of the village shall petition the board of county commissioners, the existing or original civil township shall be divided and the area of the village and the area of the balance of the original civil township shall be set apart and each organized into a separate civil township. The said petition shall describe the original civil township, the area of the village and give the approximate number of legal voters therein, describe the area of the balance of the original civil township and give the approximate number of legal voters therein and state that it is the wish of the signers that the original civil township be divided and that the village area and the area outside the village be set apart and each organized as a separate civil township; said petition shall have endorsed thereon and attached thereto an affidavit of three or more of the signers that it is signed by sixty percent of the legal voters of the area outside the village area.
SDCL 8-1-20