(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) A minimum speed limit, below which no person shall drive a vehicle except when necessary for safe operation or in compliance with law, may be displayed on appropriate traffic-control devices.

21 Del. C. 1953, § 4171; 54 Del. Laws, c. 160, § 1; 57 Del. Laws, c. 670, § 13A; 60 Del. Laws, c. 700, § 8; 60 Del. Laws, c. 701, § 44.;