N.H. Rev. Stat. § 265:76
Notwithstanding the provisions of RSA 265:75 to the contrary, the selectmen of any town may, upon such conditions as they may specify, permit the holding of time trials of motor vehicles on class V and class VI highways and the director of parks and recreation, department of natural and cultural resources, may, upon such conditions as he may specify, permit the holding of time trials of motor vehicles on class III highways within the town, provided that such roads shall be closed to other vehicle traffic during the time of such trials, and provided further that the trials are sponsored and supervised by a duly organized corporation or association registered for the purpose with the secretary of state.
RSA 265:76
RSA 263:59-b. 1971, 237:1. 1981, 146:1, eff. Jan. 1, 1982. 2017, 156:14, I, eff. July 1, 2017.