Okla. Stat. tit. 47, § 47-11-804: Minimum speed regulation

(a) No person shall drive a motor vehicle at such a slow speed

as to impede the normal and reasonable movement of traffic except

when reduced speed is necessary for safe operation or in compliance

with law.

(b) Whenever the State Highway Commission or local authorities

within their respective jurisdictions determine on the basis of an

engineering and traffic investigation that slow speeds on any part

of a highway consistently impede the normal and reasonable movement

of traffic, the Commission or such local authority may determine and

declare a minimum speed limit below which no person shall drive a

vehicle except when necessary for safe operation or in compliance

with law.