President-elect Donald Trump intends to follow through on his plan to impose sweeping tariffs on America’s top trading partners — a move that could come at a high cost to U.S. consumers. On Monday, Trump promised a new tariff on all products entering the U.

Mexico and Canada are the United States’ top two trading partners, accounting for nearly 30% of trade volumes.

Donald Trump has announced 25% tariffs on Mexico and Canada. Here is how they would work and what such tariffs might mean.