N.H. Rev. Stat. Ann. § 1:10

Upon a determination of need, the commissioner of the department of transportation may issue a permit for the alteration or resetting of the original boundary or mark upon approval of the adjoining state. Conditions for the alteration or resetting shall be determined by the commissioner and all costs borne by the applicant. A full description of any change in such monument or mark, signed by a representative of both states, shall be recorded with the secretary of state.