The Pan-American Invert stamp was issued in conjunction with the Pan-American expo held in Buffalo, NY in 1901. 6 commemorative stamps were issued by the USPS to coincide with the expo. All stamps in the series were issued with colorful border featuring black and white images in the middle of various forms of transportation. These 6 stamps carry scott catalog numbers 294-299.
The two color printing on these stamps is what made the risk of errors higher. Three of the denominations (1 cent, 2 cent and 4 cent) were printed with inversions. The 1 cent invert is the most valuable even though it is also the most common. These stamps carry scott catalog number 294a, 295a and 296a. The catalog value for a set of these 3 stamps is $100,000.
In 2001, for the 100 year anniversary, the USPS created a reproduction of this famous invert.
 2001 3505 Pan American Expo Invert Stamps SS of 7 MNH  US $9.99
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 3505 Pan Am Invert S S USPS 625 Commemorative Panel US $21.95
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 1901 US Two Cent Pan American Inverted Sterling Silver US $19.99
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 US Stamps Pan Am Inverts Inverted Jenny Siegel 2007 Auction US $9.99
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 Cat no 3505 Pan American Exposition Invert Stamps US $11.73
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 US Stamp Pan Am 294A Inverted Center Mint LH $12500 US $9,999.00
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 US 3505 Pan Am Expo Invert Stamps PRESS SHEET 4 PANES US $35.00
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 US 3505 Pan American Expo Invert Stamps Ceremony Prog US $21.60
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 USA Stamps Pan American Expo Invert Cent Used Sheet US $12.95
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 Set of 3 PAN AMERICAN Invert stamps on 2001 FDC US $18.00
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