S.D. Codified Laws § 31-12A-1.2
As used in this chapter, the term, eligible voter, has the meaning specified in this section. Only persons or public corporations that are landowners of land located within the proposed or existing road district are eligible to vote in the formation election or any subsequent election of a road district, except as provided in this chapter. An eligible voter may reside within or outside the district. Any firm, partnership, limited liability company, association, estate, or corporation that holds title to land located within the proposed or existing road district is entitled to one vote and may designate an officer or agent to vote on its behalf by presenting a written instrument to that effect to the election officials. The vote of any eligible voter who is a minor or a protected person as defined by § 29A-5-102, may be cast by the parent, conservator, or legal representative of the minor or protected person. However, if more than one person holds an interest in a lot, tract, or parcel of land, no more than one vote may be cast in any election with respect to any one lot, tract, or parcel of land, as the owners may among themselves determine.
As used in this chapter, the term, landowner, means any owner of land other than a governmental entity, as evidenced by records in the offices of the register of deeds and the clerk of courts in the county containing a proposed or existing road district. If land is sold under a contract for deed that is of record in the office of the register of deeds in the county in which the land is situated, the individual purchaser of the land, as named in the contract for deed, is treated as the landowner.
SDCL 31-12A-1.2