§ 1181. Minimum speed regulations. (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 a minimum speed limit has been established as authorized
in sections sixteen hundred twenty or sixteen hundred forty-two, no
person shall drive at a speed less than such minimum speed limit except
when entering upon or preparing to exit from the highway upon which such
a minimum speed limit has been established, when preparing to stop, or
when necessary for safe operation or in compliance with law.