Title 40, Chapter 6, Section 184
(a)(1) 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.
(2) On roads, streets, or highways with two or more lanes allowing
for movement in the same direction, no person shall continue to
operate a motor vehicle in the most left-hand lane at less than
the maximum lawful speed limit once such person knows or should
reasonably know that he is being overtaken in such lane from the
rear by a motor vehicle traveling at a higher rate of speed,
except when such motor vehicle is preparing for a left turn.
(b) Whenever the commissioner of public safety or the commissioner
of transportation or local authorities determine on the basis of any
engineering and traffic investigation that slow speeds on any part
of a road under their respective jurisdictions impede the normal and
reasonable movement of traffic, such commissioners jointly, or such
local authorities, may determine and declare a minimum speed limit
below which no person shall drive a vehicle except when necessary
for safe operation, and that limit shall be effective when posted
upon fixed or variable signs.