Washington Abe Lincoln and Alexander Hamilton recently got makeovers to thwart high-tech counterfeiters, but it may take awhile for millions of vending machines nationwide to recognize them.
To read the new $5 and $10 bills issued in May, vending machines need to be equipped with special software.
Of an estimated 6 million food and beverage vending machines that accept $5s and $10s in the United States, only 1 million of them thus far have been modified to recognize the redesigned bills, said Larry Felix, the Bureau of Engraving and Printing's lead official on the matter, citing industry figures.
Vending machine owners are scrambling to upgrade their equipment to accept the new bills, a process that will take some time, Felix said. But he was confident that the changeover would go smoothly.
Brian Allen, a spokesman for the National Automatic Merchandising Assn., said some changes were simple while others were difficult.
"Generally, speaking," he said, "we are working as fast we can."
The Treasury Department's Bureau of Engraving and Printing supplied some of the new notes to vending equipment companies at the end of last year, giving them time to develop software to recognize the bills and test it on vending machines.
Some vending machines take $20 bills which got a facelift in 1998 but many more take $5 and $10s, Felix said.
"That's a large leap a much bigger job" for the industry, he said.
Only about 10 percent of the new $5s and $10s are now in circulation, Felix said. The old bills will continue to be accepted and recirculated until they wear out.
Allen, of the vending machine association, said some vending machine operators were waiting to phase in the changes as the new bills come into wider circulation.
"It's an expense and business decision on their part," he said.