Canada is preparing dollar-for-dollar tariffs on American goods after negotiations with the Trump administration collapsed, escalating a trade dispute that could raise prices and disrupt some of North America’s most integrated industries. The retaliation will begin September 8 and target U.S. steel, dairy products, electronics, appliances, agricultural equipment, pulp and paper. The announcement came hours after the United States imposed 50% tariffs on roughly $20 billion of Canadian imports. For investors, the immediate tariffs are only part of the risk. The deeper concern is that Washington and Ottawa are losing confidence in the trade framework that has connected their factories,...