Even the U.S. Treasury Department’s Bureau of Engraving and Printing admits it doesn’t quite know why U.S. paper money is green.
However, here is the story of how it originally happened.
During the mid-1800s, the Treasury Department learned that counterfeiters were using the new medium of photography to make nearly perfect copies of currency.
They added colors to thwart the counterfeiters, which worked for a while because color film did not yet exist.
When green currency was photographed, it turned a telltale gray. However, the counterfeiters soon discovered ways to remove the colored inks.
Then they could photograph the money and ink the colors in manually.
Abraham Lincoln’s secretary of the treasury, Salmon P. Chase, contracted with the American Bank Note Company to create colored inks that would be as difficult to erase as black inks.
The most successful of the early ink formulations was green ink, so Chase decided to print all new currency with green ink on the back. Some of the first recipients were Union soldiers, who promptly dubbed the new bills “greenbacks.”
What started as a practical solution became a tradition.
Green money is what Americans have come to expect and trust. So green money is what Americans still have a century and a half later.