In 1918, a Washington clerk spent $24 on 100 stamps during his lunch break. Every plane was upside down, one later sold for $2 million

A Washington clerk walked into a post office during his lunch break on May 14, 1918, and bought something that appeared ordinary: a sheet of 100 new 24-cent airmail stamps. Then William Robey noticed something was wrong. Every Curtiss JN-4 biplane printed on the sheet was upside down.

What followed turned the sheet into one of the most famous errors in stamp-collecting history — the Inverted Jenny. More than a century later, individual stamps from that sheet have become multimillion-dollar collectibles.

The mistake that created a fortune

The 24-cent airmail stamp was among America's early stamps featuring an airplane. Its design required two separate color applications, meaning each sheet had to pass through the printing process twice. That created an opportunity for something to go wrong.


On Robey's sheet, the airplane portion was printed upside down in relation to the red frame and lettering. Robey apparently understood almost immediately that he had found something unusual. But he did not alert postal officials until after completing the purchase.

Postal inspectors arrived at his workplace within hours and questioned Robey and his wife. However, they did not have legal grounds to seize the stamps. And Robey refused to surrender the sheet.

That evening, the valuable piece of paper reportedly traveled around Washington, D.C., with Robey as he rode streetcars. He and his wife were said to have slept poorly, with the sheet hidden beneath their bed. A week later, Robey took it to Philadelphia and sold it to stamp dealer Eugene Klein for $15,000. His original investment had been just $24.

From $24 to $15,000 — and then $20,000

Klein subsequently sold the sheet to wealthy collector Colonel Edward Green for $20,000. Green made a decision that would permanently change how the Inverted Jenny is collected. Instead of preserving the sheet as one piece, he had it divided into individual stamps.

He numbered the backs of the stamps according to their positions on the original sheet before distributing them among friends and associates. That is why collectors today refer to individual Inverted Jennys by position numbers. The division also meant that the original sheet — the object at the center of the story — no longer existed as a complete collectible.

One block was stolen in 1955

Among the collectors who eventually owned Inverted Jennys was Ethel McCoy. She purchased an intact block of four stamps in 1936 for $16,000. The four stamps were positions 65, 66, 75 and 76. In 1955, McCoy lent the block to the American Philatelic Society for a convention. It was stolen.

Two of the four stamps were eventually recovered. Position 66 has never been found, and no suspect was identified in connection with the theft. Position 76 resurfaced in 2016 after a young man in Britain brought it to a New York auction house. He had inherited the stamp without knowing its history.

The FBI and the U.S. Attorney's Office for the Southern District of New York became involved, and the stamp was eventually returned to the American Philatelic Research Library, which held McCoy's claim.

One stamp spent a century in a bank vault

The story of Position 49 took a very different path. The stamp remained in a family's bank vault for roughly a century, protected from the light and never placed in a collector's album. When it finally appeared at auction in November 2023, its condition helped make it particularly desirable. Scott Trepel of Robert A. Siegel Auction Galleries described its centering as exceptional, saying, "There's no 98. There's no 100." The stamp sold for a hammer price of $1.7 million.

After the buyer's premium was added, the final price reached $2,006,000, making it the most expensive single American stamp ever sold at auction at the time.

The buyer was real estate developer Charles Hack, who already owned another Inverted Jenny.

Why the original error mattered

The Inverted Jenny's enormous value isn't simply about an airplane being printed upside down. The rarity came from a very specific combination of circumstances. The stamp required two passes through the press. A rushed press operation during wartime created the opportunity for an error, while the people handling the stamps did not immediately catch it.

And then Robey happened to buy an entire sheet.

Had the mistake been discovered before the stamps reached him, postal officials might have prevented the sheet from entering the collecting world. Had Robey not recognized its significance, the story could have ended very differently. Instead, a $24 purchase became the starting point for one of America's most valuable philatelic stories.

A different kind of rarity

The U.S. Postal Service later revisited the Jenny design. In 2013, it issued a $2 souvenir sheet featuring a reprint of the famous design. It also produced 100 panes in which the airplane was correctly oriented. The panes were sealed so buyers could not inspect them before purchase.

A subsequent Postal Service inspector general investigation concluded that producing the corrected panes violated internal rules concerning the creation of artificial rarities for profit. The report said only 20 of the 100 corrected panes were officially registered as sold.