Owners of franchises for the operation of electric street railways propelled by means of tracks and trolleys shall have full power and authority under such franchises to extend such transportation system by means of buses or other self-propelled vehicles, and such transportation shall be and become a part of the general transportation system of such street railway company, subject to all regulations imposed on such vehicles by law. Laws 1925, c. 97, p. 146, § 1.
Oklahoma Legal Code