President Trump’s threats to put a 25 percent tariff on most Canadian and Mexican imports—now on hold for 30 days, pending negotiations with both countries—have overturned the reigning orthodoxy in trade and diplomacy. Unlike his tariffs on China, the tariffs on Canada in particular lack any direct national security rationale. He may be pursuing them because he thinks Canada’s rules on fentanyl precursors are too loose, because he wants to shock the global trade system, or even because it’s his opening salvo in a bid to induce Ottawa to join the Union. But whatever Trump’s true aims are, one thing is clear: the tariffs would affect the nearly half a trillion dollars of goods and services that Americans import from Canada each year and lower near-term living standards up and down the North American continent.
