Okla. Stat. tit. 68 § 706
It is hereby declared to be the purpose of the levy in Section 705 of this title to provide funds for the construction and maintenance of county highways and permanent bridges in such counties and for these purposes it is hereby expressly provided that the special fuel use tax levied by Section 705 of this title shall be apportioned and distributed monthly by the Tax Commission to the several counties in the following manner: one-third (1/3) on area, one-third (1/3) on rural population, defined as including the population of all municipalities with a population of less than five thousand (5,000) according to the latest Federal Decennial Census, and one-third (1/3) on county road mileage, as last certified by the Department of Transportation, as each county bears to the entire area, rural population and road mileage of the state. The funds apportioned pursuant to this section shall be used in accordance with and subject to the provisions of subsection B of Section 500.6 of this title.
Okla. Stat. tit. 68, § 706