he United States has lost nearly 5 million manufacturing jobs since 2000 alone, hollowing out factory towns all over the country and leaving countless working-class Americans struggling. Getting those jobs back is a goal that politicians of all stripes eagerly line up behind. But the plain truth is that, legally speaking, there's not a lot that Trump or any other president could do to bring those jobs back, without an act of Congress. Presidents simply don't have the power to tell companies whom to hire or where to manufacture, says Jeffrey Bergstrand, professor of finance at the Mendoza College of Business at the University of Notre Dame. "Firms are going to make the decisions for their shareholders. If he wants to do this, he is going to have to use government institutions and laws to restrict the decisions of firms," Bergstrand says. And it's not at all clear Congress would support such an effort. What presidents can do is try to make it tough for companies that ship jobs overseas to make money in the United States, by imposing tariffs on their products. Trump has often talked about doing so. Presidents do have the power to impose tariffs unilaterally in the interest of national security, although it's rarely been done, says Chad Bown, senior fellow at the Peterson Institute for International Economics.