Donald Trump’s threats to democracy – including his promise to govern as a dictator on “day one” and his refusal to abide by the norm of a peaceful transition of power – are often called unprecedented. While commentators and journalists are rightly focused on the danger of the moment, there are precedents for what we face today. Three examples, far from minimizing the current danger, show both how fragile American democracy has always been and how American citizens can fight successfully to save it. The first example of a presidential threat to democracy came close to the founding. The second...