Century Aluminum’s smelter in Hawesville, Ky. The Chicago-based company pushed hard for the original 10% tariff on foreign-made aluminum.

Photo: bryan woolston/Reuters

The Trump administration’s decision to reinstate tariffs on Canadian aluminum is a victory for one small U.S. company that out-lobbied competitors wary of imposing new barriers on a key trading partner.

Canada was included in the 10% tariff when it was imposed on foreign-made aluminum in March 2018. The Trump administration exempted the country about 14 months ago, as it sought to advance negotiations on a new trade agreement with Canada and Mexico. The administration reimposed the duty on Canadian aluminum starting Aug. 16.

Chicago-based Century Aluminum Co., CENX 1.87% which had pushed hard for the original 10% tariff, lobbied for the restart of duties on Canada as a way to boost slumping U.S. aluminum prices.

Reinstating the tariff on Canada attracted opposition from more than a dozen other aluminum companies including Alcoa Corp., AA 3.56% Novelis Inc. and Arconic Corp. ARNC 1.84% They urged the Trump administration to instead pressure China to stop what they say are unfair government subsidies that encourage excess aluminum production and drag down prices.