Police in International Falls are warning businesses on both sides of the border to watch out for phony American money.
Investigator Willi Kostiuk says four phony American 20's have turned up in the Falls since last Thursday.
Kostiuk says the bills' texture and lack of certain security identifiers give them away.
The bills also come with the serial number GI53550403A.
So far, none of the bills have been found in Fort Frances.