The Incumbency Advantage in the US Congress: A Roller-Coaster Relationship
| Author | Daniel Stockemer,Rodrigo Praino |
| Date | 01 October 2012 |
| DOI | 10.1111/j.1467-9256.2012.01438.x |
| Published date | 01 October 2012 |
| Subject Matter | Research Article |
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P O L I T I C S : 2 0 1 2 V O L 3 2 ( 3 ) , 2 2 0 – 2 3 0
doi: 10.1111/j.1467-9256.2012.01438.x
Research Article
The Incumbency Advantage in the US
Congress: A Roller-Coaster Relationshipponl_
1438
220..230220..230
Daniel Stockemer
University of Ottawa
Rodrigo Praino
University of Connecticut
While every student in American politics knows that the incumbency advantage grew post-1965,
it is less clear as to whether or not this growth has been sustainable throughout the 1980s, 1990s
and 2000s. Focusing on the last three decades, we show that the electoral margins of sitting
members of the House of Representatives have not linearly grown over the past 60 years. On the
contrary, the constant increase in incumbents’ vote shares between the 1960s and 1980s could not
be sustained in the 1990s. In fact, in the 1990s, the incumbency advantage dropped sharply to
levels experienced in the 1960s. In recent years, the electoral margin of sitting House members
seems to have grown again to levels comparable to those in the 1970s.
Keywords: incumbency advantage; House of Representatives
Introduction
Scholars of American politics treat the growth of the incumbency advantage in the
US Congress in the 1960s in an almost axiomatic fashion. Since David Mayhew
(1974) declared the ‘vanishing of the marginals’ in House elections and provided
some descriptive evidence of the growth of the incumbency advantage after the
1960s, most electoral analyses take for granted that a ‘pre-’ and a ‘post-1960s’ exists,
with 1965 being the conventional watershed date. However, while numerous
analyses (e.g. Cox and Katz, 1996; Mayhew, 1974) have established that the electoral
margins of House members increased in the 30 years between 1960 and 1980, it is less
clear whether incumbents’ vote gains continued to increase in the following decades
(Abramowitz, Alexander and Gunning, 2006; Petrocik and Desposato, 2004).
This article tests the growth of the incumbency advantage for the past 60 years. We
find that Mayhew’s (1974) analysis of the increased electoral margins of sitting
members of Congress provides only a partial description of the development of the
incumbency advantage. In fact, while the overall electoral advantages enjoyed by
incumbents grew between the 1960s and the 1980s, it appears that in more recent
years such advantages have been declining. More specifically, we find that in the
© 2012 The Authors. Politics © 2012 Political Studies Association
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1990s the overall incumbency advantage seems to stand roughly at the levels
registered in the 1960s, while in the 2000s it moved to levels comparable to those
in the 1970s.
Our analysis is simple and straightforward. First, we briefly review some of the
existing works dedicated to the study of the incumbency advantage in the United
States, demonstrating how the pre- and post-1960s paradigm influenced their
analyses. Second, we present some descriptive evidence that casts some doubt on
the substantial difference between the role that the incumbency advantage played
in the 1950s and 1960s and its role in successive years. Third, we introduce two
different ways to measure the incumbency advantage, namely the difference in the
vote a sitting member of Congress receives in any given election as compared to his
or her first electoral victory. Based on these two measures, we estimate two simple
univariate statistical models that confirm our hypothesis of the growth and decline
of the incumbency advantage over the years. In conclusion, we summarise the
main argument of this article and provide some avenues for future research.
The growth of the incumbency advantage:
consequences of a paradigm
The incumbency growth paradigm holds that incumbent US House candidates have
seen an increase in popular electoral support since the mid-1960s. Mayhew (1974)
laid its foundation in the Congress literature. In his seminal work Congressional
Elections: The Case of the Vanishing Marginals, he analysed electoral data between 1956
and 1974. He concluded that, in the 1970s, incumbent congressmen had a much
better chance of winning elections with larger electoral margins than in the past
(Mayhew, 1974, p. 304) and that ‘congressional seat swings [were] declining in
amplitude’ (Mayhew, 1974, p. 313). By providing a watershed point after which the
incumbency advantage started to grow significantly (i.e. the mid-1960s), Mayhew
(1974) influenced all subsequent research on the topic. Supported by his seminal
findings, a large body of future works (e.g. Abramowitz, 1975; Ferejohn, 1977;
Fiorina, 1977; Mann and Wolfinger, 1980; Coates, 1995; Cox and Katz, 1996;
Herrera and Yawn, 1999) has taken the existence of the incumbency advantage and
its growth for granted and shifted the attention to its possible explanations, such as
the growth of bureaucracy (Fiorina, 1977), the change in relations between incum-
bents and constituents (Fenno, 1978; Romero, 2006) or the influence of the media
(Prior, 2006).
However, it is rather peculiar that the incumbency advantage has been treated in a
static manner with a focus on the ‘pre-’ and ‘post-1960s’ paradigm. Admittedly, the
growth of bureaucracy or the changing relations between voters and candidates are
potentially still valid explanations if the incumbency advantage followed the tra-
jectory of the 1960s and 1970s in subsequent decades. However, if the dynamics
surrounding the incumbency advantage have actually changed at any given point
within the past 50 years, then its causes might have to be – at least partially –
changed accordingly. In this sense, it is somewhat surprising that more recent
studies (e.g. Coates, 1995; Herrera and Yawn, 1999) have persistently taken the
continued growth of the incumbency advantage for granted.
© 2012 The Authors. Politics © 2012 Political Studies Association
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