An 1844 Hoyt's Letter Express cover sent to Rochester, New York is valued at $30,000-40,000 ahead of a sale at Robert A Siegel.
The lot will lead the auction of the Dr Carmen A Puliafito Collection of US Independent Mails in New York on May 4.
It features the only known Hoyt's multiple, with one stamp displaying the "Lettcr" error (featured on only one other stamp).
Only nine stamps survive.
Hoyt's Letter Express ran for a short time between July and September 1844. It operated along New York's Genesee Valley Canal between Rochester and Danville.
The cover also displays stamps from Pomeroy's Letter Express and Boyd's City Express, which carried the envelope on to its destination in New York City.
Siegel comments: "Considering that the first United States Postmasters' Provisionals would not be issued until nearly one year after this was mailed, and the first General Issue two years after that, the presence of six stamps in three colors from three different stamp-issuing entities on this letter must have been perceived as extraordinary, even in 1844 when it was delivered to Pierpont & Hotchkiss.
"Today, it is one of the undisputed icons of American postal history."
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