A 1901 1c Pan-American centre invert is among the highlights of Robert A Siegel's July 28-29 sale in New York.
It's expected to sell for around $12,500.
The lot was one of a series of stamps issued during the 1901 Pan-American exposition, which exhibited the technological advances.
It was also the scene of President William McKinley's assassination by anarchist Leon Czolgosz.
The stamps were only sold during the six months the show was open and are highly sought after among collectors today. This 1c invert was one of a number discovered in post offices across the US.
While it's the most common error in the series, it remains valuable. The finest known specimen sold for $19,000 at Siegel in 2009.
A rare 8c violet brown US Inland Revenue (USIR) watermark error stamp is valued at $12,000.
The auction house explains: "The "USIR" (United States Internal Revenue) watermark error occurred when a supply of paper reserved for revenue stamp production was used for printing the 6c and 8c postage stamps.
"There are approximately 75 known of the 8c with approximately ten unused, but many are either off-center or have flaws."
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