Anti-Counterfeiting Measures Through History

Counterfeiting has been a persistent threat to currency throughout U.S. history. The Bureau of Engraving and Printing and the Treasury Department have continuously evolved security features to stay ahead of counterfeiters. Understanding this evolution provides insight into why modern notes are far more difficult to counterfeit than older ones.

Colonial and Revolutionary Era Counterfeiting

Early American currency was extremely vulnerable to counterfeiting:

Printing technology was relatively simple and accessible
Colonial notes used basic printing methods with minimal security features
British counterfeited Continental Currency extensively during the Revolution to undermine the American economy
By the 1700s, counterfeiting was so prevalent that many people refused to accept paper money, preferring coins

1800s: Early Anti-Counterfeiting Innovations

Throughout the 1800s, various security innovations were attempted:

Complex engraving – Intricate designs made reproduction difficult with the technology of the time
Multiple colors – Using several ink colors made it harder to reproduce with single-color printing
Microprinting – Tiny text visible only under magnification
Serial numbers – Tracking enabled identification of counterfeits when gaps in numbering appeared
Security fibers – Threads embedded in paper for authenticity verification

Despite these measures, counterfeiting remained a significant problem through the early 20th century.

1990s Security Thread and Color-Shifting Ink

In 1996, the Treasury introduced major security features to modern currency:

Security thread – An embedded plastic strip containing "USA" and the denomination, visible when held to light. The thread's position, color, and design vary by denomination.
Color-shifting ink – Ink that changes color when the note is tilted, on the number or seal. This required sophisticated printing technology not widely available.
Watermark – A faint portrait watermark visible when held to light, matching the main portrait on the note

These features made counterfeiting dramatically more difficult and expensive, greatly reducing counterfeit currency in circulation.

2000s: EURion Constellation

A subtle but effective security measure was introduced:

EURion Constellation – A pattern of small circles arranged in a specific constellation pattern. Most modern color copiers and scanners detect this pattern and refuse to copy images containing it.
This prevents casual copying with office equipment, protecting against the most basic counterfeiting attempts
The placement is subtle enough that it doesn't affect the note's appearance

2010s: 3D Security Ribbon

The 2013 redesign of the $100 bill introduced cutting-edge security:

3D Security Ribbon – An embedded ribbon with images (the Liberty Bell) and numbers that shift and change depending on the viewing angle
Bell in Liberty Bell – A subtle image hidden within the large Liberty Bell engraving on the back
Enhanced color-shifting ink – More sophisticated transitions than previous versions

These features require extremely specialized manufacturing equipment, making casual counterfeiting nearly impossible.

Why Modern Currency Is Harder to Counterfeit

Modern anti-counterfeiting measures target multiple vulnerability categories:

Paper composition – Cotton-linen blend can't be easily reproduced on regular paper
Ink formulation – The specific inks have color-shifting properties requiring proprietary technology
Embedded elements – Security threads and watermarks require specialized manufacturing equipment
Design complexity – Modern engravings are far more intricate than older designs
Varied features – Multiple overlapping security features mean a counterfeiter must replicate all of them successfully

The Ongoing Challenge

Despite these advances, counterfeiting remains a serious federal crime. The Secret Service estimates that approximately 1 counterfeit note exists for every 10,000 genuine notes in circulation, a very low rate historically. As counterfeiting technology improves, the government continues to add new security features and upgrade existing ones.