Okla. Stat. tit. 69, § 4023

The Department of Transportation shall contract to erect and maintain, on the right-of-way of interstate and controlled access highways, logo signs informing the public of gas, food, lodging and camping facilities. The contractor shall furnish, install, maintain, and replace signs for the benefit of advertisers who provide gas, food, camping and lodging facilities for the general public, and lease advertising space on the sign to operators of these facilities.