U.S. Customs and Border Protection officials report seizing $900,000 in counterfeit cash – all of it in singles.

The dollar bills were discovered in December at the International Falls Port of Entry in Minnesota in a rail shipment originating from China, per a statement from CBP.

An investigation found 45 cartons filled with singles, which were confirmed to be fake by the Secret Service.

“CBP officers strive every day to protect the United States from a variety of threats,” said Jason Schmelz, a CBP port director, in a statement. “Those threats don’t always come in the form of terrorists or narcotics, but also in the form of counterfeit currency and other goods that have the potential to harm the economy of the United States."

The counterfeit money was seized and will be sent to the Secret Service.

Single-dollar bills, according to the Federal Reserve, have stayed the same since 1963 because the "note is infrequently counterfeited."

There is also a provision in the annual Financial Services and General Government Appropriations Act that prohibits the bill's redesign.

"Thanks to the dedication of our officers and our partnership with the Secret Service, we were able to keep this currency from entering into circulation," Schmelz said.

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