How much national forces shape Congressional election outcomes ebbs and flows. In Nationalized Politics, Jamie L. Carson, Joel Sievert, and Ryan D. Williamson document how nationalization—the degree to which national forces influence Congressional and state-level elections—has evolved since the Founding.

Using an impressive and unusually comprehensive set of election return data, the authors find that nationalization was high during the nineteenth and early twentieth centuries before declining, hitting a low point after World War II and then rebounding sharply during the 1990s before hitting unprecedented heights in the twenty-first century. The authors conclude that nationalization can arise from different factors. In the mid-nineteenth century, the causes of nationalization were institutional. Parties provided the ballots. The choices were the Democratic or Republican ballot, meaning people were forced to choose between the two slates and “ticket splitting” was difficult. Nationalization declined once states changed electoral institutions and adopted the secret ballot in the late nineteenth century. This change ushered in an era of low nationalization that lasted throughout most of the twentieth century. People frequently split their tickets, and incumbent politicians were able to carve out bases of support that were independe