Special meetings of the township electors may be held for the purpose of electing township officers to fill vacancies that occur, or for the purpose of transacting any lawful business if the entire board of supervisors files or if two members of the board of supervisors, together with at least twelve other resident voters of the township, file in the office of the township clerk a written statement that a special meeting is necessary for the interests of the township. However, special meetings may be called in a township with a population of twenty or fewer resident voters by the entire board of supervisors or by two members of the board of supervisors and four resident voters of the township.
SDCL 8-3-3