Trucks cross into the United States from Canada on the Gordie Howe International Bridge on September 6, 2026. | Jeff Kowalsky/AFP via Getty ImagesThis story appeared in Today, Explained, a daily newsletter that helps you understand the most compelling news and stories of the day. Subscribe here.I spent Labor Day weekend in Montreal, and signs of the trade war were everywhere. On Google Maps, which — at least until we crossed over the border — jarringly displayed the label “Lake America” where “Lake Ontario” used to be. Along Highway 2, which runs beside the St. Lawrence River, and where lawns sprouted signs with slogans like “Canada, strong and free.” On the TV in the hotel lobby, where a brisk CBC segment reported that Canadians overwhelmingly support Prime Minister Mark Carney’s retaliatory tariffs against the US.Those tariffs, incidentally, went into effect this morning — targeting roughly $20 billion in US products. The levies are Canada’s response to the 50 percent tariffs that President Donald Trump slapped on Canadian goods in late August, after trade talks between the two countries collapsed. They’ll make it harder for American businesses to sell goods ranging from cheese to golf clubs in Canada, and they’ll make those goods more expensive for Canadians. More worryingly, the new tariffs inflame an ugly dispute that, as I unpack more below, has no apparent upside for the US. President Donald Trump’s aggression toward our northern neighbor has both damaged the country’s international reputation and made life more expensive for average Americans.Go a little deeperView LinkLaunching a trade war against America’s closest ally is self-evidently…unusual, let’s say. But the strangest thing about Trump’s campaign against Canada is how few people are riding this particular train. No think tank is churning out anti-Canada papers. No industry is lobbying for 50% tariffs. No prominent influencer, even, has caught Trump’s eye with dreams of northern conquest. This sets Canada apart from virtually all of Trump’s other unpopular, fringe positions, which at least have some constituency behind them. Since Trump began musing about Canadian annexation 18 months ago, however, reporters have repeatedly gone out in search of the intellectual and political roots of that fixation…and come back empty-handed. My colleague Zack Beauchamp made another go of it just last month and concluded, in a word: ¯\_(ツ)_/¯. Zack talked to a ton of trade experts, political scientists, and Republican strategists and found that — even in industries that have long-standing trade disputes with Canada, and even at think tanks that support economic nationalism more broadly — no one is advocating for the full-scale trade war we’re now experiencing.That vacuum has led many analysts to conclude that Trump’s animus toward Canada is personal, not strategic. And while armchair-psychologizing about this president is risky, his posts about Canada certainly give the impression that he’s after personal and geopolitical domination more than anything else. On Sunday, Trump posted a cartoon that shows him and Carney dressed as hockey players, with Carney sprawled on the rink in apparent distress. Trump glowers over him: “GET UP, GOVERNOR,” a speech bubble says. It might be the most insight we get into the real motivations for a trade war that’s steadily intensifying, with no resolution in sight. One link for later➨ Ditch the plastic food packaging. A new peer-reviewed study concluded that it’s impossible to evaluate the safety of most chemicals used in food processing and packaging — companies just don’t make enough data public for that. So in the absence of regulation that mandates more disclosure, you’re probably better off storing your food in an eclectic collection of tiny jars.Before you go… Did you know…that rats probably don’t deserve all the blame for the Black Death? Researchers are investigating a surprising and gross range of potential plague-carriers, including sheep, lice, fleas, and camels. Today’s trivia: Skye is the largest island in what archipelago? (You can find this and other brain puzzles in Vox’s daily crossword. Look for the answer in tomorrow’s edition.)Yesterday’s trivia: Last week we asked you for the world’s second-largest living bird. That would be the emu, which can reach 130 pounds and run at speeds of up to 31 miles per hour.