Minn. Stat. § 370.10: COMMISSIONER VACANCIES DUE TO BOUNDARY CHANGES.

If a change in the boundaries of a county abolishes a commissioner district or districts in the county, by the removal of all the territory of the district or districts from the original county, or otherwise, or creates a vacancy or vacancies in the board of county commissioners of the original county, and the board of county commissioners is left with less than five members, with an even number of members, or with more than five members, to complete a board consisting of an odd number of members, or at least five members, a special election shall be held as provided by section 375.101, except that the person shall be elected at large within the changed boundaries of the original county.