You’ve probably seen the image before. It’s a tiny, rectangular scrap of paper with a red frame and a blue biplane in the center. Only, the plane is flying on its back. It’s called the Inverted Jenny, and honestly, it is the most famous screw-up in the history of the United States Post Office. Most people call it the upside down plane stamp, and if you happen to find one in an old attic, you aren't just looking at a piece of mail history—you’re looking at a winning lottery ticket worth hundreds of thousands of dollars.
It’s weird, right? In almost any other industry, a manufacturing defect makes a product worthless. If your car comes off the line with the engine upside down, you’re filing a lawsuit. But in the world of philately, a mistake is a miracle. The Inverted Jenny has become more than just a stamp; it’s a symbol of rarity that bridges the gap between dusty hobbyists and high-stakes investors.
How a Post Office Clerk Handed Out a Fortune
The year was 1918. The United States was launching its very first airmail service. This was a big deal. To celebrate, the Post Office Department decided to issue a special 24-cent stamp featuring the Curtiss JN-4HM, affectionately known as the "Jenny." Because the stamp used two colors—red and blue—each sheet had to be fed through the printing press twice.
That’s where things went sideways. Or, well, upside down.
Basically, at least one sheet of 100 stamps was fed into the press the wrong way during the second pass. This meant the blue airplane was printed inverted inside the red frame. On May 14, 1918, a man named William T. Robey walked into a post office in Washington, D.C. He asked for a sheet of the new airmail stamps. When the clerk slid the sheet across the counter, Robey’s heart probably skipped a beat. He saw 100 little planes flying upside down. He paid $24 for the sheet. Within days, he sold it for $15,000.
Think about that for a second. In 1918, $15,000 was a massive sum of money. Today, the upside down plane stamp from that original sheet can fetch upwards of $500,000 to $1.5 million depending on its condition. One single stamp!
Why the Inverted Jenny Captured Our Imagination
There are rarer stamps out there. The British Guiana 1c Magenta is a one-of-a-kind specimen that sold for nearly $10 million. But nobody knows what the British Guiana 1c Magenta is unless they are a hardcore collector. Everyone knows the Jenny.
It’s iconic. It’s visual. It’s easy to understand. You don't need a degree in history to see why it's special. It’s just a plane doing a loop-de-loop.
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The story of the upside down plane stamp is also fueled by the drama of the "Lost Jennys." See, Robey sold his sheet to a dealer, who then sold it to a wealthy collector named Eugene Klein. Klein then sold it to Colonel H.R. Green. Green, being a bit of a character, decided to break the sheet up. He wanted to sell individual stamps and blocks to other collectors. Because he did this, we know exactly where most of these stamps ended up. They have pedigree. They have "census" numbers.
But some went missing. Some were stolen. One was famously used to mail a letter (can you imagine being the person who licked a million dollars and stuck it on an envelope?). Another was nearly lost in a vacuum cleaner. These stories turn a piece of paper into a legend.
Spotting a Fake: Not Everything Upside Down is Gold
If you go on eBay right now and search for an upside down plane stamp, you’ll see dozens of them for $5 or $10. Obviously, these aren't the real deal.
The market is flooded with reproductions, "reprints," and outright forgeries. In 2006, the U.S. Postal Service actually played a bit of a trick on collectors. They issued a souvenir sheet of Inverted Jennys, but they were modern 2-dollar versions. To make it spicy, they printed a very small number of "upright" Jennys—stamps where the plane was actually right-side up—as the rare variety. It was a clever flip of the original mistake.
How to tell if you're looking at a real 1918 Inverted Jenny:
- The Paper: The original 1918 stamps were printed on "flat plate" presses. The paper has a specific texture and thickness that modern digital printers can't replicate.
- The Perforations: Real Jennys have a perforation gauge of 11. Most fakes are off by just a hair.
- The Ink: Under a microscope, the blue ink of the plane should sit on top of the red ink in a very specific way.
- The Gum: The back of an unused stamp has "original gum" (OG). If it’s been licked or stuck in an album, the value drops, but it’s still worth a house.
Honestly, if you find one, don't touch it with your fingers. Oils from your skin can ruin the value instantly. Use stamp tongs. Better yet, call a reputable auction house like Robert A. Siegel Auction Galleries. They’ve handled more Jennys than almost anyone else in the world.
The Most Famous Heist in Stamp History
You can’t talk about the upside down plane stamp without talking about the McCoy block. In 1955, a block of four Inverted Jennys was stolen from a convention in Norfolk, Virginia. It belonged to a collector named Ethel McCoy. For decades, the stamps were gone. Vanished.
They started popping up one by one over the years. One was recovered in 1958. Another in 1982. But it wasn't until the 2000s that the final pieces of the puzzle started coming together. These stamps had been "cleansed"—their margins trimmed to hide their identity. It’s a gritty, weird underworld that most people don’t associate with stamp collecting.
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It proves that this isn't just a hobby for people in cardigans. It’s a high-stakes game of hide and seek with millions of dollars on the line.
What an Upside Down Plane Stamp Costs Today
Pricing is all over the place because condition is everything. Philatelic experts use a grading scale, usually from 1 to 100.
A "Very Fine" (VF 80) stamp might sell for $300,000. But if you get into the "Superb" territory (95 or 98), the price skyrockets. In 2023, a single Inverted Jenny—the finest known copy from the original sheet—sold at auction for a staggering **$2 million**. It was the most expensive single United States stamp ever sold.
Why the jump? It’s about "eye appeal." Some of the stamps were centered poorly. Some have small creases. But this particular copy was basically perfect. It looked like it had just come off the press yesterday. For the ultra-wealthy, these stamps are like Picassos. They are "alternative assets" that usually hold their value better than the stock market.
The Cultural Impact of a Mistake
The upside down plane stamp has popped up in The Simpsons (Homer finds a sheet at a yard sale and tosses it, saying "The plane's upside down!"). It’s been in movies and novels. It represents the "big find."
It’s also a reminder of a time when the government actually made things by hand. Today, everything is automated. If a digital file is wrong, the printer stops. Back then, it was just a guy named George Eaves who accidentally put the paper in the wrong way.
We love the Jenny because it’s human. It’s a mistake that became a masterpiece.
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How to Start Your Own Hunt
You aren't going to find a 1918 Jenny at your local post office. But the "hunt" is what makes collecting fun. Most people start by looking through "kiloware"—huge boxes of used stamps sold by weight.
You’re looking for errors. It doesn't have to be the upside down plane stamp. Look for "color shifts" where one color is printed slightly off-center. Look for "imperf" stamps that are missing the little holes around the edges.
If you’re serious about the Inverted Jenny specifically, your best bet is to follow the big auction houses. Even if you can’t afford to bid, the catalogs are like history books. They tell the story of every individual stamp, tracking who owned it in 1940, 1970, and today.
Practical Steps if You Think You Found One
- Don't lick it. Seriously. Moisture is the enemy.
- Protect it. Put it in a PVC-free plastic sleeve or a dedicated stamp glassine envelope.
- Get a "Cert." You need a certificate of authenticity. The Philatelic Foundation or the American Philatelic Expertizing Service (APEX) are the gold standards. They will examine the paper, ink, and perforations.
- Research the "2013 Version." Remember, the USPS issued a $2 version in 2013. If your stamp says "$2" on it, it's the modern one. If it says "24 CENTS," you might be rich.
- Check the edges. If the stamp has straight edges on two sides, it might be from the corner of the sheet. Those are actually very desirable to certain collectors.
The world of the upside down plane stamp is deep. It’s a mix of history, art, and cold hard cash. Whether you’re a billionaire looking for a place to park some money or just someone who likes a good story, the Inverted Jenny remains the ultimate "what if" of the collecting world. It’s proof that sometimes, doing everything wrong is the only way to get it perfectly right.
If you're looking to dive deeper into this world, your next move should be visiting the National Postal Museum's online gallery. They have high-resolution scans of the Jenny that allow you to see the actual ink fibers. It’s the best way to train your eye to see what a "real" million-dollar mistake looks like before you start hunting through those old boxes in the garage.
Check your local library for a copy of a Scott Catalogue. It’s the "bible" for stamp values. Even if you don't find a Jenny, you might find a different error that’s worth more than the envelope it's stuck to. Keep hunting. The next big find is usually hiding in the last place anyone thinks to look.