More than 20 lumber mills closed across B.C. over the last three years. Billions in wood products affected by U.S. tariffs. Tens of thousands of jobs lost in Canada. …While there are many factors driving the decline, recent U.S. tariffs haven’t helped. But Donald Trump is hardly the first U.S. president whose government has imposed steep duties on Canadian lumber. The tariffs are the latest chapter in a dispute that’s been going on for more than four decades. …It boils down to differences in how much Canadian and American producers have to pay for access to wood, according to Export Development Canada (EDC). …U.S. reaction is divided, with the lumber industry largely supportive, and those forced to pay higher prices for building materials — such as the National Association of Homebuilders —  opposed. …The U.S. Lumber Coalition’s van Heyningen applauded the tariffs.