Under such regulations and subject to such terms and conditions as the Secretary of the Treasury shall prescribe—
(1) any common carrier of merchandise owning or operating a railroad, steamship, or other transportation line or route for the transportation of merchandise in the United States,
(2) any contract carrier authorized to operate as such by any agency of the United States, and
(3) any freight forwarder authorized to operate as such by any agency of the United States,
(June 17, 1930, ch. 497, title IV, § 551, 46 Stat. 742; Dec. 28, 1945, ch. 605, 59 Stat. 667; Pub. L. 87–598, Aug. 24, 1962, 76 Stat. 400; Pub. L. 87–854, Oct. 23, 1962, 76 Stat. 1130; Pub. L. 90–240, § 3, Jan. 2, 1968, 81 Stat. 776.)