A horizontal pair of US 1847 5c red brown stamps on an 1851 Canadian cover will star in an upcoming stamp auction at Robert A Siegel.

The 1851 postal treaty between the US and Canada allowed for pre-paid Canadian stamps to be issued and accepted across the border in America.

The cover dates to May 1851, after the introduction of the US-Canada postal treaty

This led to the release of the first official Canadian stamp, the three cent beaver. Prior to that, and in a few months after the treaty was ratified, the 1847 US issue was used.

The present lot was cancelled on May 2, 1851 - well over a month after the treaty went into effect.

The auction house comments: "This is the finest cover showing use of the 5-cent 1847 issue to pay all of the Canadian postage during the treaty period, which commenced on April 6, 1851.

"Any cover with the 1847 issue used from Canada is rare, but covers mailed during the treaty period with the stamps cancelled by the Canadian target are the rarest and most desirable of all.

"This magnificent cover was featured in the 1956 Caspary and 1957 Dick sales, and, since the European connoisseur acquired it 58 years ago for his collection, it has been unavailable to the philatelic market."

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