The retaliatory rate against Great Britain, in this example applied in Philadelphia in July 1848.
In June 1847, when the Ocean Line began the first American transatlantic packet service, Great Britain charged the full incoming steamship rate (24 cents) on each letter. A year later the U.S. responded to the British one-shilling discriminatory rate against American packets with a 24 cent charge on both incoming and outgoing British packet letters, added to inland postage.
This letter was sent from Liege, Belgium on 19 July 1848 via British mail. It departed Liverpool on 22 July aboard Cunard’s America, which arrived at New York on 4 August. The Philadelphia post office charged 29 cents due: 24 cent retaliatory charge against Great Britain plus 5 cents postage from New York.