N.H. Rev. Stat. Ann. § 28:7-b

For each unincorporated town or unorganized place, the county in which it is located and its commissioners shall have the same responsibilities and powers to exercise planning, zoning, subdivision and related regulations as city and local land use boards. Regulations shall be exercised in accordance with the provisions of RSA 672-677 to the extent practical, in order to ensure reasonable development and planning in the unincorporated town or unorganized place.