No vehicle shall be turned so as to proceed in the opposite direction upon any curve, or upon the approach to or near the crest of a grade, where such vehicle cannot be seen by the driver of any other vehicle approaching from either direction within 500 feet.
N.H. Rev. Stat. Ann. § 265:43
Turning on Curve or Crest of Grade Prohibited
Source
Official source: New Hampshire General Court. Reproduced from public-domain New Hampshire statutes; confirm against the official source for the current text. Not legal advice.