President Donald Trump signed three proclamations on Monday imposing additional 50% tariffs on a range of Canadian goods, invoking Section 338 of the Tariff Act of 1930 — a provision that has gone unused since at least 1949, with law firm Covington and Burling finding no public record of its use since that year [Source: CNBC]. Washington cited what it described as discriminatory Canadian measures against US alcohol, automobile and dairy products. The tariffs are set to take effect 30 days after signing.

Each of the three proclamations covers a distinct set of Canadian imports, with targeted goods including wine, milk and cream, hockey equipment and cement. Major resource categories — energy, potash, fish and critical minerals — are excluded from the new duties, as are goods already subject to separate sector tariffs such as autos and steel. A senior administration official confirmed the 50% rate is the maximum permitted under Section 338, which grants the president authority to impose duties of up to that level on goods from countries found to be discriminating against the United States. Notably, the tariffs apply even to goods that would otherwise qualify for preferential treatment under the US-Mexico-Canada Agreement.

The administration grounded each proclamation in specific grievances. On alcohol, a senior US official said all but two Canadian provinces and territories had halted the purchase, distribution or retailing of US alcoholic beverages without imposing equivalent restrictions on goods from other countries. On autos, Trump's proclamation cited Canada's maintenance, from April 2025, of a 25% tariff on imports of US motor vehicles that did not qualify for USMCA preferential treatment. Officials were explicit that the action was 'solely in response' to the alleged discriminatory measures and was separate from any tariffs related to Canadian wildfires, though the president had separately asked aides for options on that front [Source: The Washington Times]. The senior official added that the US remains open to discussions with Canada, particularly in the context of the USMCA review process, but that no formal negotiations are currently underway.

The move escalates a prolonged trade dispute between Washington and Ottawa. The two countries engaged in an escalating tariff fight through 2025, with the Trump administration imposing heavy duties on Canadian goods and Canada retaliating — making it, according to a senior administration official, one of the only nations besides China to have done so. That backdrop has weighed on the broader trade relationship: the July 1, 2026 deadline for Canada, the US and Mexico to review and potentially extend the USMCA for a further sixteen years passed without agreement, shifting the pact to annual reviews ahead of its scheduled 2036 expiry. Earlier in July, the Trump administration confirmed it would not seek to renew the agreement outright. Against that backdrop, the Bank of Canada held its policy rate at 2.25% on July 15, its sixth consecutive hold, while trimming its 2026 growth forecast. No same-day market reaction data was available at the time of publication.

Sources: Bloomberg, CNBC, ABC News, Associated Press, The Washington Times, Barchart