Why Did The Incumbency Advantage In U.S. House Elections Grow?

In the last twenty years, scholars have scrutinized the electoral advantages conferred by incumbency-both at the federal and at the state level-more than perhaps any other factor affecting U .S. legislative elections.1 Much of the literature focuses on explaining why the incumbency advantage in U .S. House elections grew so substantially, starting in the mid-1960s. The dominant contenders in the literature are two, one emphasizing resources of various kinds (Mayhew 1974) and opportunities to perform constituency services (Fiorina 1977; 1989), one emphasizing partisan dealignment (Erikson 1972; Burnham 1974; Ferejohn 1977). While not incompatible, these explanations do point to significantly different factors as key, and neither has emerged as a clear winner. In this paper, we suggest a new approach to measuring the incumbency advantage, one that disaggregates the total value of incumbency into three components. By examining the trends over time in these three components we find evidence suggesting that much of the growth in the incumbency advantage at the federal level cannot be accounted for by resource growth; rather, some version of the dealignment story will have to be employed.