The new import taxes could affect manufacturers that rely on steel and aluminum. Manufacturers aren’t just going to switch to domestic suppliers, said Erin McLaughlin, senior economist at The Conference Board, because those suppliers can’t expand steel and aluminum factories overnight. That takes years.

That’s about to double. In a proclamation issued Tuesday, Trump confirmed that the U.S. will begin taxing nearly all steel and aluminum imports at 50% after the clock strikes midnight Wednesday. Steel and aluminum from the U.K., meanwhile, will continue to be levied at 25% due to a recent trade deal.

Trump administration tariffs on all imported aluminum and steel are now in effect as the United States launched a 50% duty directly on those materials Wednesday.