B. 1. Each county shall be reapportioned by the board of county commissioners on or before October 1 following the final official publication of the Federal Decennial Census to this state for the purposes of legislative redistricting. Provided, for purposes of the 2021 reapportionment of counties, each county shall be reapportioned by the board of county commissioners on or before November 30, 2021, following the final official publication of the Federal Decennial Census to this state for the purposes of legislative redistricting. The reapportionment shall be recorded in a resolution adopted by the commissioners. The resolution shall include an effective date for the reapportioned county commissioner districts. The effective date shall be January 1 of the following year; provided, however, county election boards shall conduct regular or special elections for county commissioner held after April 5, 2022, in accordance with the reapportioned districts.

2. Beginning with the reapportionment following the 1990 Federal Decennial Census, all boundaries of county commissioner districts shall follow clearly visible, definable and observable physical boundaries which are based upon criteria established and recognized by the Bureau of the Census of the United States Department of Commerce for purposes of defining census blocks for its decennial census.

3. If the commissioners fail to reapportion the county as required by this subsection, the commissioners shall be subject to the provisions of Sections 91 through 105 of Title 51 of the Oklahoma Statutes and it shall be the duty of the county excise board to perform the reapportionment.