WV Const., Article IX, Section 8

Formation of new counties. No new county shall hereafter be formed in this state with an area of less than four hundred square miles; nor with a population of less than six thousand; nor shall any county, from which a new county, or part thereof shall be taken, be reduced in area below four hundred square miles, nor in population below six thousand. Nor shall a new county be formed without the consent of a majority of the voters residing within the boundaries of the proposed new county, and voting on the question.