42 U.S.C. § 7472 — Initial classifications

(a) Areas designated as class I: When this part was enacted, all of the following areas that existed on August 7, 1977, became class I areas and may not be redesignated: (1) international parks; (2) national wilderness areas larger than 5,000 acres; (3) national memorial parks larger than 5,000 acres; and (4) national parks larger than 6,000 acres. All areas redesignated as class I under regulations issued before August 7, 1977, are class I areas that may be redesignated as provided in this part. The boundaries of areas designated as class I under this section must reflect boundary changes that occurred after August 7, 1977, or that may occur after November 15, 1990.

(b) Areas designated as class II: All areas in a State^* that section 7407(d) designates as attainment or unclassifiable, and that are not established as class I under subsection (a), are class II areas unless redesignated under section 7474.