You’ve probably held one a thousand times and never really looked at it. Most people just check for the blue 3D ribbon on the front, make sure Benjamin Franklin looks legit, and move on. But the back of a new 100 dollar bill is honestly where the most interesting engineering is happening. It’s not just a picture of a building. It’s a massive, coordinated effort to stay three steps ahead of North Korean "supernotes" and high-end digital scanners.
Money is weird. We trust these slips of cotton and linen because the government says they have value, but the physical design is what keeps that trust from evaporating. Since the 2013 redesign—which was actually delayed for years because of printing "creasing" issues—the $100 note has become the most sophisticated piece of paper on the planet.
That Big Gold Number 100
The first thing you notice on the back of a new 100 dollar bill is that giant, vertical "100" in the corner. It's bright gold. It’s obnoxious. And it’s there for a very specific reason: the visually impaired.
For a long time, the U.S. was criticized because all our bills felt the same. If you’re blind, a $1 and a $100 are identical by touch. While we still don't have different sizes or Braille-style bumps like the Euro or the British Pound, that massive high-contrast 100 helps people with low vision identify the denomination quickly.
But there’s a secret in the ink.
If you tilt the bill, you’ll notice that gold doesn't just shimmer—it’s part of a color-shifting system. The Bureau of Engraving and Printing (BEP) uses something called Optically Variable Ink (OVI). Basically, there are tiny flakes of specialized film in the ink that reflect light differently depending on the angle. On the front, the "Bell in the Inkwell" does this too. On the back, that huge 100 is a primary defense against photocopiers. Scanners can’t replicate the way light bounces off those metallic flakes. They just see a flat, muddy brown.
Independence Hall: Not Just a Pretty House
The centerpiece of the back of a new 100 dollar bill is Independence Hall in Philadelphia. But look closer. This isn't the same drawing they used on the old "small head" bills from the 1920s through the 90s.
When the BEP redesigned the note, they actually changed the perspective of the building. We’re now looking at the rear of Independence Hall. Why? Because the engraving needed to be more complex to thwart digital recreations. Every single brick, every window pane, and the tiny clock face are created through intaglio printing.
Intaglio is a fancy word for "it's literally engraved into a metal plate." When the paper is pressed against the plate with tons of pressure, the ink stays slightly raised. If you run your fingernail across the back of the bill, you can feel those ridges. If it feels smooth as a greeting card, you’re holding a fake.
And check the time on the clock. On the old bills, the hands were usually set to 4:10. On the back of a new 100 dollar bill, the time is 10:30. There’s no big conspiracy theory here, despite what some corners of the internet say. The BEP just likes to refresh the artwork to make it harder for counterfeiters who are using old printing plates.
The Microprinting Maze
You might need a magnifying glass for this part. Or a really good smartphone camera.
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The U.S. Treasury loves hiding words where you can’t see them. On the back of a new 100 dollar bill, there is microprinting that is almost impossible to replicate with a standard inkjet printer. Look at the borders of the note. You’ll see "THE UNITED STATES OF AMERICA" repeated in letters so small they look like a solid line to the naked eye.
Counterfeiters hate this. When you try to scan and print microprinting, the dots of ink from a commercial printer bleed together. Instead of crisp, legible letters, you get a blurry, jagged mess.
Why is there so much "Empty" Space?
If you hold the bill up to a light, you’ll see that the "empty" space on the right side of the back of a new 100 dollar bill isn't actually empty. That’s where the watermark of Benjamin Franklin lives.
Because the watermark is embedded inside the paper fibers and not printed on top, it’s visible from both sides. This is a classic security feature, but it’s still one of the most effective. Most high-end fakes try to bleach a $5 bill and print a $100 on top of it. But if you do that, the watermark will still be Abraham Lincoln.
Always check the face in the light. If the face on the watermark doesn't match the face on the bill, someone is trying to pull a fast one.
The "EURion Constellation" and Why Your Scanner Hates You
Ever tried to scan a $100 bill to put it in a PowerPoint or a joke flyer? Your printer probably gave you a stern warning or just refused to work.
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This is because of the EURion Constellation.
On the back of a new 100 dollar bill, if you look at the sky above Independence Hall, you’ll see tiny, yellow "100s" scattered around. They look like a random pattern, but they aren't. They are arranged in a specific geometric pattern that photo editing software like Photoshop and hardware like Xerox machines are programmed to recognize.
The moment the software sees those five little points in that specific orientation, it shuts down the operation. It’s a global standard. It’s why you can’t just "Ctrl+P" your way to wealth.
The Paper Isn't Actually Paper
Technically, the back of a new 100 dollar bill is printed on a blend of 75% cotton and 25% linen. That’s why it doesn’t fall apart in the wash.
If you look really closely at the back, you’ll see tiny red and blue fibers embedded in the material. These aren't printed on. They are mixed into the pulp before the paper is even made. In the past, counterfeiters would try to draw these on with fine-tip pens. Now, the BEP uses a proprietary synthetic thread that is even harder to mimic.
How to Spot a Fake Using Only the Back
While most people focus on the front, the back is a goldmine for verification.
- The Scratch Test: Run your nail over the "THE UNITED STATES OF AMERICA" text. It should be "toothy" and raised.
- The Color Shift: Watch the large 100 in the corner. It should transition smoothly from copper to green. If it’s just shiny glitter, it’s a fake.
- The Light Test: Flip it over and look for the security thread. On the $100 bill, the thread glows pink under UV light and says "USA 100" vertically. You can see the shadow of this thread from the back if you hold it up to a lamp.
The back of a new 100 dollar bill is a masterpiece of security. It’s a mix of 18th-century engraving techniques and 21st-century material science. Next time you're lucky enough to have one in your wallet, take ten seconds to actually look at it. The level of detail is honestly staggering.
If you're handling a lot of cash, your next best move is to invest in a cheap UV flashlight. Even the most sophisticated "supernotes" often fail the UV glow test on the internal security thread. Also, pay attention to the "feel"—if the paper feels unusually thick or waxy, the intaglio printing is likely fake. Stay sharp and trust your hands more than your eyes.