Mere talk of tariffs will spur some consumers to run out and buy big-ticket items, or stockpile smaller ones, on the theory that prices will soon rise. That behavior, alone, could make prices increase . If Trump announces tariffs on his first day in office, as he has suggested, some prices could spike immediately.

Donald Trump's tariff plan would affect products from Canada, Mexico, and China. Here's what to know about tariffs, who pays them, and how they work.