Nationalization and the Incumbency Advantage

Legislative scholars have investigated both the growth in the incumbency advantage since the early 1970s and its decline in recent decades, but there are several unanswered questions about this phenomenon. In this paper, we examine the incumbency advantage across a much wider swath of history to better understand its connection with changing levels of electoral nationalization. Based on an analysis of U.S. House elections extending back to the antebellum era, we find that the incumbency advantage fluctuates in predictable ways over time with changes in nationalization, which can be a product of both institutional and political conditions. We also demonstrate that the increased influence of local forces in congressional elections may not be strictly necessary nor sufficient for the existence of an incumbency advantage.