US paper currency is among the most secure in the world, featuring multiple layers of protection that make counterfeiting extremely difficult. Understanding these features not only helps you spot fake bills but also gives you a deeper appreciation for the engineering behind every bill.
The Evolution of Currency Security
American currency has continuously evolved to stay ahead of counterfeiters. The most significant redesigns occurred in 1996, 2004, 2006, 2008, 2013, and 2017, each introducing new security measures that leverage cutting-edge technology.
Key Security Features by Denomination
The $100 Bill (Series 2009A and newer)
The hundred-dollar bill contains the most advanced security features:
3D Security Ribbon Look for the blue ribbon woven into the paper. When you tilt the bill, the images of bells change to 100s, and they appear to move side to side.
Color-Shifting Bell in the Inkwell The copper-colored bell in the inkwell on the front of the bill shifts to green when tilted.
Portrait Watermark Hold the bill up to light to see a faint image of Benjamin Franklin to the right of the portrait.
The $50 Bill (Series 2004 and newer)
Color-Shifting Ink The numeral 50 in the lower right corner shifts from copper to green when tilted.
Security Thread A thin embedded strip that glows yellow under UV light. The thread is positioned to the right of the portrait.
Watermark A watermark of Ulysses S. Grant is visible when held up to light.
The $20 Bill (Series 2004 and newer)
Color-Shifting Ink The numeral 20 in the lower right corner changes from copper to green.
Security Thread The embedded strip glows green under UV light and is located to the left of the portrait.
Microprinting Look for tiny text that reads "USA TWENTY" and "USA20" in various locations.
During CashScan's development, we studied security features across modern denominations to improve our scanning engine. That said, AI scanning is best at identifying denominations and series; small details like microprinting quality or subtle ink variations are things only a careful human inspection will reliably catch. There are some that are not detectible by anything other than the human eye.
Universal Security Features
Regardless of denomination, all modern US bills share these features:
Paper Composition
US currency paper is 75% cotton and 25% linen, giving it a distinctive feel that's difficult to replicate. The paper also contains red and blue security fibers embedded randomly throughout.
Intaglio Printing
The portraits and borders are printed using intaglio printing, which creates a raised texture you can feel with your fingertips. Run your finger across the portrait, and you should feel distinct ridges.
Federal Reserve Indicators
Each bill displays the Federal Reserve Bank that issued it through:
- A seal with the bank name
- A letter designation (A through L)
- A corresponding number (1 through 12)
Serial Numbers
Every bill has two identical serial numbers: one on the upper right and one on the lower left. These numbers are unique to each bill and printed in a distinctive font.
How to Authenticate a Bill
When checking if a bill is genuine, use this quick checklist:
- Feel the texture - Genuine bills have a crisp, slightly rough feel
- Check the color-shifting ink - Tilt the bill and watch for color changes
- Look for the watermark - Hold it up to light
- Find the security thread - Also visible when held up to light
- Examine the printing quality - Portraits should be sharp and detailed
- Feel the raised printing - Run your finger across the portrait
Using Technology for Verification
While knowing security features is valuable, technology can make verification faster and more reliable. CashScan uses advanced image recognition to:
- Identify all visible security features
- Check for inconsistencies
- Compare against known genuine bills
- Provide detailed analysis of any bill
This is especially useful for:
- Small business owners
- Collectors evaluating purchases
- Anyone handling large amounts of cash
Why Security Matters
Counterfeiting isn't just illegal; it undermines trust in our monetary system. The Secret Service estimates that approximately $70 million in counterfeit currency is currently in circulation, though this represents a tiny fraction of the over $2 trillion in genuine currency worldwide.
By understanding and checking security features, you help:
- Protect yourself from fraud
- Support the integrity of the financial system
- Catch counterfeits before they spread further
Stay Informed
Currency security continues to evolve. The Federal Reserve periodically releases redesigned notes with enhanced security features. Stay updated by:
- Following announcements from the Bureau of Engraving and Printing
- Using apps like CashScan to learn about new features
- Familiarizing yourself with bills whenever a new series is released
Understanding what makes your money secure is both fascinating and practical. The next time you handle a bill, take a moment to appreciate the sophisticated technology in your hands, and verify it's the real thing. For more on currency collecting, see our guides on how to start collecting paper money and rare dollar bills worth money.
