SDCL § 31-13-12: County aid roads--Designation by county commissioners.

The board of county commissioners of each county is hereby empowered to designate in its discretion township roads or roads in unorganized townships within the county, as it may deem advisable and in the public interest as "county aid roads," and to expend any funds available from the county highway funds for laying out, constructing, graveling, and maintaining such township roads or roads in unorganized townships so designated as "county aid roads."