Book excerpt: An urgent, historically-grounded take on the four major factors that undermine American democracy, and what we can do to address them. While many Americans despair of the current state of U.S. politics, most assume that our system of government and democracy itself are invulnerable to decay. Yet when we examine the past, we find that to the contrary, the United States has undergone repeated crises of democracy, from the earliest days of the republic to the present. In The Four Threats, Robert C. Lieberman and Suzanne Mettler explore five historical episodes when democracy in the United States was under siege: the 1790s, the Civil War, the Gilded Age, the Depression, and Watergate. These episodes risked profound, even fatal, damage to the American democratic experiment, and on occasion antidemocratic forces have prevailed. From this history, four distinct characteristics of democratic disruption emerge. Political polarization, racism and nativism, economic inequality, and excessive executive power – alone or in combination – have threatened the survival of the republic, but it has survived, so far. What is unique, and alarming, about the present moment is that all four conditions are present in American politics today. This formidable convergence marks the contemporary era as an especially grave moment for democracy in the United States. But history provides a valuable repository from which contemporary Americans can draw lessons about how democracy was eventually strengthened — or in some cases weakened — in the past. By revisiting how earlier generations of Americans faced threats to the principles enshrined in the Constitution, we can see the promise and the peril that have led us to the present and chart a path toward repairing our civic fabric and renewing democracy.