The shipment came from China.
U.S. Customs and Border Protection says its officers seized $900,000 in counterfeit money from the International Falls Port of Entry.
The agency says the counterfeit money was found in a commercial rail shipment that originated in China.
Officers found 45 cartons of counterfeit $1 bills with a fake value of $900,000 last month during a customs inspection.
The Secret Service was contacted and determined the currency was counterfeit.