Tempus Edax Rerum: Measuring the incumbency advantage in the U.S. House of Representatives

Many studies provide valuable insight on the electoral incumbency advantage; however, little work provides insight or an organized theory for how such an advantage develops for career politicians. We develop such a theory, arguing that to understand the incumbency advantage at the time of an electoral victory, it is necessary to consider the length of each specific congressional career. We find that the total share of the incumbent vote received has a curvilinear relationship with the number of years any House Member spends in office. Our findings also result in a better understanding of the incumbency advantage in the U.S. then previous conceptualizations and allows for comparisons of the incumbency advantage across the two Chambers of Congress, other elective offices, and even across democratic political systems.

► We develop a theory on how incumbency unfolds within congressional careers.
► Years spent in office and total share of the vote have a curvilinear relationship.
► Incumbency conceptualized as time in office provides several advantages.