In this chapter: I. "Council" means the New Hampshire transportation council. II. "Government agency" includes any department, agency, commission, public corporation, bureau, authority, instrumentality, or political subdivision of: (a) The United States of America. (b) The state of New Hampshire. (c) Any state adjacent to New Hampshire. III. "Municipality" means town as defined in RSA 21:5. IV. "Regional planning commission" means any commission formed pursuant to RSA 36:46.