Canada’s new tariffs on roughly $20 billion worth of American goods officially took effect Tuesday, matching earlier U.S. levies dollar-for-dollar.
The duties of 15 to 50 percent target steel, dairy, appliances, agricultural equipment, paper products, and electronics.
Ottawa imposed the measures in response to U.S. tariffs on Canadian imports that began weeks earlier.
The move marks another sharp deterioration in relations between the two longtime allies.
President Trump has framed the dispute as necessary to protect American industry; Canadian officials describe it as an unprovoked assault on integrated supply chains.
Alberta’s honey industry, which produces 40 percent of Canada’s output, is already feeling the combined pressure of weather problems and the trade fight.
Border communities that once treated the line as a formality now report strained personal and commercial ties.
Economists warn the tit-for-tat measures will raise prices for consumers on both sides and complicate planning for manufacturers that have treated North America as a single market for decades.
Negotiations have not resumed.
