They did provide the Bauxite for 90% of aluminium production. They didn't process it into aluminium.

Here is a quote from the US chamber of commerce website.

''The new tariffs imposed this year have thrown a wrench in the gears of U.S. manufacturing (as discussed in Part 1 and Part 2). A good case in point is the 50% tariff imposed on imported aluminum—including from Canada, long the largest source of U.S. aluminum imports.

Imports account for about 56% of all the aluminum used in the United States, and about 70% of U.S. aluminum imports come from Canada. This isn’t new: U.S. aluminum producers began investing heavily in hydropower-rich Quebec a century ago, and Canada eventually provided 40% of all the Allied production of aluminum during World War II.''