Pivotal Tuesdays: Four Elections That Shaped the Twentieth CenturySerious and silly, unifying and polarizing, presidential elections have become events that Americans love and hate. Today's elections cost billions of dollars and consume the nation's attention for months, filling television airwaves and online media with endless advertising and political punditry, often heated, vitriolic, and petty. Yet presidential elections also provoke and inspire mass engagement of ordinary citizens in the political system. No