A US 1847 10c black on an 1848 cover is to star in the auction of the Steven Walske Collection of US-France Transatlantic Mail at Robert A Siegel.
The lot dates to the retaliatory rate period and is valued at $40,000-50,000.
The rate was introduced by the British in 1847, in response to American packet ships starting to service the transatlantic route following several years of British monopoly.
The British continued to charge the full rate (34c) on mail carried on American ships on arrival at port.
In the case of the present lot, the 24c difference was paid in cash.
The auction house comments: "This cover, along with the iconic "Rush cover," are the only two 1847 issue retaliatory rate uses known to France.
"This is also one of only six 10-cent 1847 issue covers to France recorded by Steven Walske from any rate period.
"[It is] a transatlantic cover of the highest order of rarity and one of the highlights of the Walske collection of United States-France transatlantic mails."
The Rush Cover, which features six specimens of the 1847 10c black, made $1.2m in a 2006 sale at Robert A Siegel.
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