The president has pitched his trade policies at workers who feel left behind by globalization. But that doesn’t mean trade barriers will revive factories and close income gaps.

Trump has justified tariffs on goods from Canada, the top U.S. export market, by accusing it of failing to stop the cross-border flow of fentanyl, even though U.S. government data shows Canada accounts for only 1% of the fentanyl that enters the United States.