If the area of any county in this state has been altered by the changing of the boundaries and the county's commissioners do not run at large, the board of county commissioners, at the first regular meeting thereafter, shall establish commissioner districts in the county. The board shall fix boundaries of each district in the manner provided by law for establishing commissioner districts and changing the boundaries of each district insofar as the same is applicable. The commissioner districts established and the boundaries fixed shall remain as established and fixed until changed as provided by law.
SDCL 7-2-13