S.D. Codified Laws § 31-12A-1.1
Notwithstanding any other provision of chapter 31-12A, an area with three or fewer landowners may be formed into a road district pursuant to this chapter. Each landowner shall be a trustee at large and no election of trustees is required.
After the district is incorporated and the number of landowners within the district is five or more, the district shall conduct an election pursuant to § 31-12A-16 to elect the board of trustees. The district shall conduct the election on the first Tuesday after the anniversary date of the formation of the district.
To serve as a trustee of a county road district that has one hundred or more eligible voters, the person shall be a resident and landowner of the district.
To serve as a trustee of a county road district with less than one hundred eligible voters, a person shall be a landowner who owns real property within the district.
SDCL 31-12A-1.1