SDCL § 32-25-5.2: Posting of minimum speeds on particular highways--Violation of minimum speeds as misdemeanor.

If the transportation commission within its respective jurisdiction determines 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 may adopt rules setting minimum speed limits below which no person may drive a vehicle except when necessary for safe operation or in compliance with law. A violation of such minimum speed limits is a Class 2 misdemeanor.