SDCL § 7-8-1: Number and terms of office of commissioners--Staggered terms.

Each organized county shall have a board of commissioners consisting of not less than three nor more than seven members, each of whom shall be elected at a general election only and whose term of office shall be four years commencing on the first Tuesday of January following election. Any commissioner who represents an even-numbered district shall run for election at the general election at which the President is elected; any commissioner who represents an odd-numbered or unnumbered district shall run for election at the general election at which the Governor is elected.