Upon the enactment of this part, all—
(1) international parks,
(2) national wilderness areas which exceed 5,000 acres in size,
(3) national memorial parks which exceed 5,000 acres in size, and
(4) national parks which exceed six thousand acres in size,
All areas in such State designated pursuant to section 7407(d) of this title as attainment or unclassifiable which are not established as class I under subsection (a) shall be class II areas unless redesignated under section 7474 of this title.
(July 14, 1955, ch. 360, title I, § 162, as added Pub. L. 95–95, title I, § 127(a), Aug. 7, 1977, 91 Stat. 731; amended Pub. L. 95–190, § 14(a)(40), Nov. 16, 1977, 91 Stat. 1401; Pub. L. 101–549, title I, §§ 108(m), 110(2), Nov. 15, 1990, 104 Stat. 2469, 2470.)