Okla. Const. art. X, § 10A

To provide funds for the purpose of establishing and maintaining or aiding in establishing and maintaining public libraries and library services, a special annual recurring ad valorem tax shall be levied when such levy is approved by a majority vote of the qualified electors of the county voting on the question at an election called for that purpose by the Board of County Commissioners, either upon its own initiative or upon petition initiated by not less than ten percent (10%) of the qualified electors of the county based on the total number of votes cast at the last general election for the county office receiving the highest number of votes at such an election.

Except as provided in this section, in a county having less than one hundred fifty thousand (150,000) population, according to the most recent Federal Decennial Census, the special annual recurring ad valorem tax levy shall be not less than one (1) mill nor more than four (4) mills on the dollar of the assessed valuation of all taxable property in the county. In a county having more than one hundred fifty thousand (150,000) population or in a multicounty library system with a county having more than one hundred fifty thousand (150,000) population, according to the most recent Federal Decennial Census, the special annual recurring ad valorem tax levy for each such county shall be not less than one (1) mill nor more than six (6) mills on the dollar of the assessed valuation of all taxable property in the county.

This special levy shall be in addition to all other levies and when authorized shall be made each fiscal year thereafter until such authority shall be cancelled by a majority vote of the qualified electors of the county voting on the question at an election called for that purpose by the Board of County Commissioners upon petition initiated by not less than twenty percent (20%) of the qualified electors of the county based on the total number of votes cast at the last general election for the county office receiving the highest number of votes at such an election.

The proceeds of such levy shall be used by the county for creation, development, operation and maintenance of such public libraries and library services as are authorized by the Legislature. Nothing herein shall prohibit other levies for public libraries and library services or the use of other public funds for such purposes. All expenditures of the proceeds of such levies shall be made in accordance with laws heretofore or hereafter enacted concerning such libraries and library services. The provisions hereof shall be self-executing.