N.H. Rev. Stat. § 237:45
For the purpose of connecting the central New Hampshire turnpike with the proposed relocation of route U.S. 3 in Massachusetts, at the New Hampshire-Massachusetts boundary, the commissioner of transportation, with the approval of the governor and council, is hereby authorized to lay out and construct a relocation of the central New Hampshire turnpike at a point westerly of the present location of said route in the city of Nashua, and to lay out and construct additional ramps at the interchange of the central New Hampshire turnpike and route 130, and for the acquisition of land necessary for continuation and construction of the F. E. Everett turnpike to the N.H.-Mass. boundary and to provide an access road or ramps north and south at Spitbrook road, provided funds are available for the construction of the additional ramps within the appropriations made hereunder for the purposes of this subdivision. Except as may be inconsistent herewith and except as hereinafter otherwise provided, said relocation shall be laid out, constructed and operated in accordance with, and shall be subject to the provisions of this subdivision including, but not limited to, RSA 237:40. Provided further that said relocation shall not be opened to traffic until relocated route 3 in Massachusetts shall also be opened to traffic.
RSA 237:45
RSA 257-A:1. 1963, 281:1. 1965, 342:1. 1981, 87:1. 1985, 402:6, I(b)(8).