Green’s Dictionary of Slang

a traffic policeman, a Highway Patrolman; also attrib.

1973		Chopper Mag. Jan. 42: [headline] BEAR KNUCKLE. Eat Hog, Smokey.
1976		Humboldt Republican (IA) 21 jan. 2/2: Smokey Bear — Any policeman on the highway. Smokey on the ground — Policeman out on patrol. Smokey on rubber — Policeman moving. Smokey dozing — Policeman stopped.
1981		G.V. Higgins Rat on Fire (1982) 89: If there was a Smokey out there tonight, you couldn’t prove it by me.
1996		Eble Sl. and Sociability 21: Smokey the Bear ‘highway patrol officer’.
2000		B. Wiprud Sleep with the Fishes 56: He removed his Smoky Bear hat.