ACROSS AMERICA — One of those $1 bills in your wallet could be worth tens of thousands or even hundreds of thousands of times more due to a government printing error that went unnoticed before the currency was put into circulation.

The U.S. Bureau of Engraving and Printing doesn’t usually make mistakes like this. Collectors can't wait to get their hands on the bills with duplicate serial numbers — “technically counterfeiting,” according to the personal finance blog Wealthynickel.com.

Mistakes like this are exceedingly rare, and that makes the misprinted bills all the more valuable, according to the American Numismatic Association, a congressionally chartered nonprofit that studies and collects bills and coins.

Depending on the condition of the bills, they could be worth anywhere from $20,000 to $150,000.

One batch of misprinted bills was issued by the federal bank in New York and the second was issued at Washington, D.C. About 6.4 million of the $1 banknotes are still in circulation, and could be anywhere in the world by this time. Only nine matching pairs of $1 bills have been located so far.

A banknote collector who goes by Silverpicker discovered that duplicate bills had been printed while poring over the Bureau of Engraving and Printing’s public documents. The collector had to file Freedom of Information Act request to get the details.

Only then did the government admit to the error.

Here’s what you need to know:

• The bills were printed in 2014 and 2016.
• On the far right of the picture of George Washington, look for “Series 2013.”
• The bill has a “B” Federal Reserve seal above the serial number, which is located to the right of Washington’s picture.
• The serial number ends with a star (*) and the affected bills fall between B00000001* – B00250000* or B03200001*- B09600000*

The Zegers/Winograd Project was established by collectors to catalog the bills and facilitate trading, but the founders stepped down in 2021 and the project more or less died. Now, a new collector has taken over the site, and bills that match the criteria can be submitted to Project 2013B to see if there’s a match.

So far, the database has about 36,000 serial numbers.

Wealthy Nickel said that so far, none of the collectors who have found matched pairs have been willing to part with them.

While you’re busy checking your singles, keep an eye out for other valuable currency.

For example, uncirculated $2 bills from 1890 could fetch up to $4,500, and uncirculated bills from almost every year between 1862 and 1917 could be worth a grand, according to U.S. Currency Auctions estimates. That site also has a tab for currency errors that may make certain bills and coins more valuable.

The printing method and location can also affect how much collectors are willing to pay.

USA Today reported that a $2 bill printed in 2003 sold through Heritage Auction for $2,400 on July 24, 2022, and later resold for $4,000.