Inverted Jenny
America's most famous stamp error — a 1918 US airmail stamp on which the biplane was accidentally printed upside down. Only 100 examples exist, making each worth over $1 million.
United States · 1918
Inverted Jenny
Overview
The Inverted Jenny is the most celebrated error stamp in American philatelic history. On May 10, 1918, the US Post Office issued a new 24-cent airmail stamp depicting the Curtiss JN-4 biplane — known as the 'Jenny' — in flight. The stamp was printed in two colors: red for the frame and blue for the center. During printing, a single sheet of 100 stamps went through the press with the center (the airplane) upside down. A stamp collector named William T. Robey noticed the error at a Washington DC post office and purchased the full sheet for $24. Within days, he sold it to a dealer for $15,000 — a fortune in 1918. The sheet was subsequently broken up and distributed among the world's most prestigious collections. In November 2023, a single Inverted Jenny sold for $2 million at Robert A. Siegel — setting a new record for a US error stamp.
Design & Technical Details
Red (carmine) border frame with 'United States Postage' and '24 Cents'. Blue center showing the Curtiss JN-4 biplane. In error copies, the blue center is printed rotated 180°, making the airplane appear to fly upside down. Each stamp has the plate number in the sheet margin.
Historical Facts
- William T. Robey purchased the error sheet for $24 on May 14, 1918
- He sold the full sheet within days for $15,000 to dealer Eugene Klein
- The sheet was subsequently sold to Colonel E.H.R. Green for $20,000
- Green had the sheet broken up; singles, pairs, and blocks were distributed separately
- In 2013, USPS honored the stamp by reprinting it with the airplane correctly oriented
- One stamp (Position 49) was missing for nearly 60 years before resurfacing in 2016
- In 2023, a single stamp sold for $2 million — more than 83,000x its original face value
How to Identify This Stamp
If you believe you may have found a Inverted Jenny, here are key identification characteristics to check:
- Genuine examples always show the airplane clearly upside down — there is no ambiguity
- The carmine frame and blue center are the two-color printing signature
- All 100 positions in the sheet have been documented; position numbers help identify specific stamps
- Look for 'C3a' in Scott Catalogue — this is the definitive reference number
- Expertization (PSE, Philatelic Foundation) is mandatory for any claimed example
- Never buy an Inverted Jenny without a certificate from a recognized expertizer
Frequently Asked Questions
How much is an Inverted Jenny worth today?
Individual Inverted Jenny stamps are worth approximately $1–2 million depending on condition and block configuration. The most recent auction record was $2 million for a single stamp in November 2023 at Robert A. Siegel Auction Galleries. Pairs and blocks command even higher premiums.
How many Inverted Jenny stamps exist?
Exactly 100 Inverted Jenny stamps exist — one complete sheet was the only error produced. The sheet was broken up in the 1920s. Today, approximately 87 stamps are accounted for. Some are held by the Smithsonian National Postal Museum; others are in private collections worldwide.
Who discovered the Inverted Jenny?
William T. Robey, a stamp collector from Washington DC, discovered the error sheet on May 14, 1918 at a post office near his office. He paid $24 for the full pane of 100 stamps — the design immediately caught his eye as an obvious printing error. He negotiated through a dealer and sold the sheet for $15,000 just four days later.
Can I find an undiscovered Inverted Jenny?
No — all 100 stamps from the only known error sheet have been accounted for. There are no known undiscovered Inverted Jennys. If you encounter someone claiming to have found a new one, exercise extreme caution — sophisticated forgeries exist and professional expertization is essential.