S.D. Codified Laws § 9-9-3
The term of office of the mayor and commissioners shall be not less than two or more than five years as determined by ordinance, except that at the first election after the adoption of the commission form of government the mayor's term shall be for five years and the commissioners shall be elected for staggered terms. If the number of commissioners is four, one shall be elected for one year, one for two years, one for three years, and one for four years. If the number of commissioners is two, one shall be elected for two years and one for four years. At the annual election preceding the expiration of the term of office of the mayor or any commissioner, a successor shall be elected for a term not to exceed five years as determined by ordinance.
SDCL 9-9-3