15 U.S. Code § 318 - Weather signals on mail cars
The Secretary of Commerce, in cooperation with the United States Postal Service, may arrange a plan by which there shall be displayed on all cars and other conveyances used for transporting United States mail suitable flags or other signals to indicate weather forecasts, cold-wave warnings, frost warnings, and so forth, to be furnished by the Secretary.
“United States Postal Service” substituted in text for “Postmaster General” pursuant to Pub. L. 91–375, § 4(a), Aug. 12, 1970, 84 Stat. 773, set out as a note under section 201 of Title 39, Postal Service, which abolished the office of Postmaster General of the Post Office Department and transferred its functions to the United States Postal Service.
Office of Chief of Weather Bureau abolished and functions transferred to Secretary of Commerce by Reorg. Plan No. 2 of 1965, eff. July 13, 1965, 30 F.R. 8819,79 Stat. 1318. Reorg. Plan No. IV of 1940 transferred Weather Bureau from Department of Agriculture to Department of Commerce. For further details, see notes set out under section 311 of this title.