Okla. Stat. tit. 69, § 69-3015: Surplus revenues

Annually, within sixty (60) days after the close of each fiscal

year of any public trust which shall have issued bonds for the

construction, operation and/or maintenance of a toll expressway, the

trustees of such trust shall pay to the State Treasurer all funds

which are not required to be used for other purposes under the terms

of the instrument creating the trust and any bond indenture executed

in connection with such expressway project, and in such event, such

surplus revenue may be appropriated by the Legislature for the

benefit of schools or public highways or both.