N.H. Rev. Stat. § 236:69
It is hereby declared to be the policy of this state and in the public interest to provide for maximum visibility along the interstate system, federal aid primary system, and turnpike system, and connecting roads or highways; to prevent unreasonable distraction of operators or motor vehicles; to prevent confusion with regard to traffic lights, signs or signals or other interference with the effectiveness of traffic regulations; to promote maximum safety, comfort and well-being of users of the interstate system, federal aid primary system, and turnpike system; to preserve and enhance the natural scenic beauty or the aesthetic features of the interstate system, federal aid primary system, turnpike system and adjacent areas; to promote the reasonable, orderly and effective display of advertising devices along such systems; and to regulate advertising devices along such systems in a manner consistent with customary use in this state. To implement this declared policy and cooperate with the United States government in the construction and maintenance of public highways in accordance with Title 23, United States Code as amended and supplemented, this subdivision provides for the regulation of advertising devices on the interstate and federal aid primary highway systems.
RSA 236:69
RSA 249-A:1. 1961, 269:1. 1969, 429:1. 1971, 245:1. 1981, 87:1, eff. April 20, 1981.