S.D. Codified Laws § 31-17-7
Adjoining townships shall contribute equally to the construction, improvement, and repair of any township highway that lies on a section line forming the boundary between the townships. However, this section and §§ 31-17-8 to 31-17-15, inclusive, do not prohibit the supervisors of adjoining townships, by a majority of the supervisors from each township, from scheduling and holding a joint meeting of their township boards to mutually agree on alternative procedures for apportioning the responsibilities and costs of constructing, altering, or repairing any township boundary line highway, bridge, or culvert. Each township clerk shall record the time and location of the joint meeting and shall immediately publish notice of the proposed joint meeting in the same manner provided in §§ 8-3-4 and 8-3-5. Any order, notice, award, or apportionment contract, and any other documents resulting from the joint meeting shall be produced in duplicate, filed with each township office, and recorded by each township clerk. Any order, contract, or mutual agreement made before July 1, 1995, between adjoining township boards of supervisors apportioning or reapportioning a township boundary line road, bridge, or culvert is hereby validated and has the same force and effect as though executed after that date.
SDCL 31-17-7