These are the 10 political dynasties in US history that lasted longest

This graphic is based on America’s Political Dynasties: From Adams to Clinton by Brookings Institution scholar Stephen Hess. Hess served in both the Eisenhower and Nixon administrations. This distillation of political power measures the depth and breadth of American political families, not necessarily their importance. The Harrisons and the Roosevelts, for instance, each produced two presidents, yet history does not weigh them equally.