Okla. Stat. tit. 69, § 69-3016: Purpose - Counties of 500,000 or more exempt

The purpose of this act is to permit necessary highways to be

constructed, operated and maintained without the expenditure of any

city, county or state tax funds, and to thus enable cities and

counties and the State Highway Department to conserve available

funds for the construction and maintenance of streets and highways

that may not be financed under the terms of this act. Provided,

however, the provisions of this act shall not apply to public trusts

created or to be created for the purpose of financing, constructing,

operating and maintaining toll expressways in counties having a

population of five hundred thousand (500,000) or more, according to

the latest Federal Decennial Census.