A historic escalation in the trade dispute with Canada arrives this week. Starting Thursday, a 50% tariff takes effect on a wide band of Canadian goods entering the United States, the first time any president has invoked Section 338 of the Tariff Act of 1930 - a Depression-era statute that had sat unused for nearly a century until three proclamations signed by President Trump on July 20 activated it against America's second-largest trading partner.
The headline targets are dairy, alcoholic beverages and motor vehicles, but the fine print reaches much further. Annexes attached to the proclamations add furniture, cement, plywood, hockey sticks, fishing rods, seeds, clothing and swimming pools to the covered list, all carrying the same 50% duty. Roughly $19.3 billion of the exposure sits in motor vehicles alone, with a further $1 billion in alcoholic beverages and about $97 million in dairy, according to trade attorneys who reviewed the filings. In total, the US Trade Representative's office estimates close to $20 billion of the roughly $382 billion in goods the US imported from Canada last year - about 5.2% - will carry the new duty.
Crucially for importers, qualifying under the US-Mexico-Canada Agreement offers no shelter this time. Unlike prior tariff rounds that exempted USMCA-originating goods, the Section 338 duties apply regardless of where a product's components were sourced, according to trade-compliance analysts tracking the rollout. That marks a break from the carve-outs that have softened the impact of tariff actions on North American supply chains since the pact took effect.
Ottawa weighs its response
Canadian Prime Minister Mark Carney has called the move a violation of the USMCA and confirmed that Ottawa is prepared to retaliate, but he has stopped short of naming specific targets. Following talks with Canada's provincial premiers, Carney said the federal government is keeping a "full range" of responses available while negotiators continue working toward a broader trade agreement, and he has signaled Canada will not move before the US tariffs formally take effect, wary of undercutting talks in the campaign's final days.
Cross-border industries are already adjusting. Automakers with integrated US-Canada supply chains, dairy cooperatives near the border and drinks distributors that rely on Canadian imports have been reworking sourcing and pricing plans since the proclamations were signed last month, with several warning that the lack of a USMCA exemption removes a safety valve companies had relied on to route around earlier duties.
The immediate market reaction has been muted, in part because the tariffs were telegraphed weeks in advance, giving importers time to front-load shipments ahead of the deadline. But the timing compounds other pressures already weighing on cross-border trade, including the July 24 rollout of separate Section 301 tariffs of 10-12.5% on imports from 60 economies. With the Court of International Trade still weighing a separate challenge to earlier tariffs imposed under emergency powers, businesses on both sides of the border are bracing for a fluid few weeks as the August 19 deadline, and any Canadian countermeasures, take shape.
