Okla. Stat. tit. 47, § 47-15-105: Department of highways to sign all state and federal

highways.

(a) The Department of Highways shall place and maintain such

traffic-control devices, conforming to its manual and

specifications, upon all state and federal highways as it shall deem

necessary to indicate and to carry out the provisions of this act or

to regulate, warn or guide traffic.

(b) No local authority shall place or maintain any traffic-

control device upon any highway under the jurisdiction of the

Department of Highways except by the latter's permission.