S.D. Codified Laws § 47-16-13
Proxy votes--Delegate votes
Voting by proxy shall not be allowed in any cooperative, except that the bylaws may provide for representation of members by delegates apportioned territorially. A delegate shall cast the votes to which members represented by him are entitled.
Source: SDC 1939, § 11.1114 (4) as enacted by SL 1965, ch 23, § 1.