RSA 265:63 Alteration of Limits.

I. Whenever local authorities in their respective jurisdictions determine on the basis of an engineering or traffic investigation that the prima facie speed permitted under this chapter is greater or less than is reasonable and safe under the conditions found to exist upon a way or part of a way, the local authority may determine and declare a reasonable and safe prima facie limit thereon which:
(a) Decreases the limit at intersections;
(b) Increases the limit within an urban district but not to more than 60 miles per hour;
(c) Decreases the limit outside an urban district but not to less than 25 miles per hour; or
(d) Decreases the limit within any business or urban residence district but not to less than 25 miles per hour.
II. Local authorities in the