As the influence of political parties diminished in postwar America, scholars argued about whether this decline was caused by changes in voter behaviour, new style of campaigning, or such trust-shattering events as Vietnam and Watergate. To some, parties were the relics of a technologically less sophisticated era. Today, however, may believe that these institutions have an inevitable tendency to adapt and survive. This text argues that neither party decline nor adaptation is inevitable and the author's state-centred approach aims to show that the condition of political parties depends critically on the state's major policy concerns and on its institutional policymaking structure. Political decisions during state-building periods shape whether parties appear relevant to governance. From the 1870s to 1930s, party competition was based substantially on trade policy; parties controlled trade policy formations, they differed significantly in their policy prescriptions, and voters and elites cared about the differences and believed parties controlled policy outcomes in this key area.In contrast, the content and policymaking structure of macroeconomic policy, a dominant concern of the postwar state, marginalized parties as important actors. By examining the formation of the postwar state, the behaviour of parties on Congress, and how parties respond to recession, this book aims to show how state structure and policy weakened American parties after the 1940s.