The US dollar is worth about 1.33 Canadian dollars, so they immediately get a 30% increase in value when they go to exchange it.  Since the U.S. and Canada are close, both physically and in terms of trade, Canadian banks maintain U.S. funds accounts for Canadians and are adept at dealing with and making U.S. to Canadian exchange super easy.  These are checking accounts which hold funds in U.S. dollars and allow the user to have checks that clear in the U.S. just like a check drawn on a U.S. bank