(1) On the third Tuesday of May of the next odd-numbered year following the appointment of the first highway district commissioners, commissioners from subdistricts one and two shall be elected for a term of two (2) years and the commissioner from subdistrict three shall be elected for a term of four (4) years. Thereafter the term of office of all commissioners shall be four (4) years.
(2)  A highway district whose terms and election were established by prior law shall convert to the election of commissioners as provided in subsection (1) of this section.
Each highway commissioner shall be elected on a districtwide basis.