In this chapter—

((1)) ** .—** The term “environs” means the territory surrounding the District of Columbia included in the National Capital region.

((2)) ** .—** The term “National Capital” means the District of Columbia and territory the Federal Government owns in the environs.

((3)) ** .—** The term “National Capital region” means—

((A)) the District of Columbia;

((B)) Montgomery and Prince Georges Counties in Maryland;

((C)) Arlington, Fairfax, Loudoun, and Prince William Counties in Virginia; and

((D)) all cities in Maryland or Virginia in the geographic area bounded by the outer boundaries of the combined area of the counties listed in subparagraphs (B) and (C).

((4)) ** .—** The term “planning agency” means any city, county, bi-county, part-county, or regional planning agency authorized under state and local laws to make and adopt comprehensive plans.