Okla. Const. art. XVII, § 4

The Legislature shall provide by general laws for the creation of new counties or altering or changing lines and the equitable division of assets and of liabilities, and the original location of county seats in such new counties: Provided, That every such question shall be submitted to the vote of the qualified electors residing in the territory to be formed into such new county or transferred to another county, and shall be approved by sixty per centum of the votes cast in said election: Provided, That no new county shall be formed of less than four hundred square miles taxable area, nor with a population less than fifteen thousand people, nor with taxable wealth less than two and one-half million dollars, as shown by the current tax rolls. Nor shall any territory be taken from an existing county for any purpose bringing the newly created line of such existing county nearer than ten miles to the county seat thereof. Nor shall the taxable area, population, or taxable wealth of said existing county be reduced below that required for a new county. Nor shall any territory, in any case, be transferred from one county to an existing county, if, by such transfer of territory, the county from which the territory be taken will then be smaller in area than the county to which the addition is made: Provided, That when territory is to be transferred from an existing county to either a new or an existing county, there must be sixty per centum of the vote cast in such particular territory in favor of the transfer, and, in case the transfer be to an existing county, the acceptance of such territory must first be approved by a majority vote of the electors of said county, at an election to be called and held therefor, as may be provided by law. The limitation as to area, valuation and population shall not be increased by the Legislature.