The board of county commissioners by unanimous vote may adopt an ordinance to increase the size of the boards of county commissioners to five members. Upon creation of a five-member board, the county shall be divided by the incumbent board of county commissioners into five county commission districts that shall be compact, contiguous and as nearly equal in population as practicable. One county commissioner shall reside within and be elected from each county commission district. Change of residence to a place outside the district from which a county commissioner was elected shall automatically terminate the service of that commissioner and the office shall be declared vacant. (As added November 3, 1992.)