A Choice, Not an Echo

This dissertation offers an intellectual and institutional history of party polarization and ideological realignment in the postwar United States. It treats the construction of an ideologically sorted party system as a political project carried out by conscious actors within and around the Democratic and Republican parties. The work of these activists, interest groups, and political elites helped to produce, by the last decades of the twentieth century, an unpredicted and still-continuing era of strong, polarized partisanship in American politics. In tracking their work, the dissertation also account for changing ideas about the party system over time, starting with an influential postwar scholarly doctrine that cast bipartisanship as a problem for which polarization would provide the solution.