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º Adam Carr's Election Archive - 2006 and Archive - 2008 of U.S. House Congressional Districts
º thirty-thousand.org - Reelection Rates of Incumbents in the U. S. House, and Duration of Representatives’ Incumbency in the U. S. House
º Dave Leip's Atlas of U.S. Presidential Elections and nationalatlas.com's Printable Maps - Congressional Districts
º Renka, Presidents and Congresses, 1933-2010

The Incumbency Advantage in the U.S. Congress
Russell D. Renka
PS103 - April 5, 2010

 º Incumbent Success Rates
 º District Design and Partisan Polarization
 º Starvation
 º Works Cited

    Incumbents are sitting Members of Congress.  The great majority of these are careerist politicians who routinely seek reelection to another term of office, and occasionally try to vault from a lower Representative's position to the more exalted title of Senator by running statewide.  There are no formal term limitations imposed upon national legislative offices.  These men and women have proven remarkably difficult to defeat for election.  Here I show this, and suggest why.

Incumbent Success Rates                 Top; Next Down

    Success of congressional incumbents has become something of a half-funny joke recently.  These are the figures for those Representatives who sought reelection in the 13 biennial national elections for 435 U.S. House seats from 1982 through 2006:  95.17% of incumbents who sought reelection were successful.  What's more, an average of 396 of the 435 incumbent seat holders sought another term, leaving only 39 "open seats" each biennium for new Members of Congress (Jacobson 2008, 28-29).  You can see these effects graphically via thirty-thousand.org - Reelection Rates of Incumbents in the U. S. House, and Duration of Representatives’ Incumbency in the U. S. House.  Rounding the 4.83% of winning challengers to 19 freshmen, another 39 get there the easy way by filling a seat vacated by a departing incumbent.  So about two-thirds (39 of 58) of freshmen only get there from good fortune of facing no incumbent.

    The midterm November 2006 election of the 110th House was a particularly bad year for Republican incumbents burdened with a highly unpopular president and the effect of their party being held chiefly responsible for the Iraq war.  Result was negative for the Republicans, as 27 incumbents who lost (23 in the House, 4 in the Senate) were entirely Republicans (2006 defeated congressional incumbents - Congresspedia).  But there were 402 House incumbents seeking reelection, and the 23 who lost represent a 5.7 percent rate of defeat (Retired, resigned and defeated members of the 109th Congress - Congresspedia).  The incumbent success rate was 379/402 = 94.3% and the RIP (reelected incumbent proportion) was 379/435 = 87.1%.  That was entirely consistent with House elections since 1982.

    It's uncommon to see such a one-sided profile of partisan losses as 2006, but the same thing in larger fashion took place in 1994, the first midterm of the Democratic Clinton Administration.  That year, 35 Democrats and 0 Republicans were losers among 382 House incumbents who sought reelection.  But more pertinently, even in these two partisan years, only 58 losers stack up next to 726 winners for a combined incumbent success rate of 92.6%.  House incumbents in the modern House are very hard to beat even in partisan years like 1994 and 2006 where control of the House was switched to a new party (Renka, Presidents and Congresses, 1933-2010).

    The Senate has not been much better:  86.98% of incumbents were winners in the 1982-to-2006 period.  Only 33.3 Senate seats on average are up each biennium (a first 33, another 33, then 34 to tally 100; and back to the first 33).  In the 13 elections of 1982 to 2006, that's 433 senators who could seek reelection; and 361 of them did so, leaving just 82 vacated open seats for new senators.  By rounding the 13.02% of challengers who broke through against incumbents to 38 freshmen, that's 85 of 113 freshmen who got there by virtue of avoiding a collision with a senatorial incumbent.  And in 2006, there were 6 incumbent senatorial losers, all Republicans.  At least one, George Allen of Virginia, was a surprising loser considering that he was prominent among those expected to contend seriously for the 2008 Republican presidential nomination.  All that's gone now.

     The year 2008 was no change in these numbers.  You can see turnover and defeats in the House here:  United States House of Representatives elections, 2008 - retiring incumbents.  The 435 members of the 110th House of 2007-08 mostly ran for reelection, with just 33 incumbents retiring, leaving 402 up for election in November 2008.  Of those, 23 lost (4 in primaries, 19 in general election) and 379 won, producing a reelection rate of 94.28% (House of Representatives elections, 2008 - defeated incumbents; also Retired, resigned and defeated members of the 110th Congress - Congresspedia).  That's about normal for this era.  The Senate saw 30 seek reelection and 6 lose, for an 80.00% reelection rate.  That too isn't far from the Senate norm (United States Senate elections, 2008 - races).  Most losers in both houses were Republicans, as 2008 proved equally bad for the GOP as 2006 was.

    Was the 1982-2008 House-Senate incumbent loss rate consistent with earlier history of incumbent losses?  No; it's only half as high as the earlier postwar loss rate.  The 17 elections of 1946-to-1980 had House incumbents scoring about a 90 percent success rate, while Senators came in at 78 percent.  Turning this data around, these were incumbent "kill rates" of about 10 percent per election in the House, and 22 percent in the more avidly sought and competitive Senate, compared to later kill rates of 5 percent House and 13 percent Senate.  A natural question is why the kill rates have been halved in both houses.

    Political mapping is one of the first suspects--for the House, but not the Senate.  Congressional elections go by five-election cycles based on using each decade's population Census to draw new congressional district lines.  That's shown by color demarcations at thirty-thousand.org - Duration of Representatives’ Incumbency in the U.S. House.  The 2000 Census brought about redrawn new congressional districts by 2002, so the 108th House convened in 2003 (blue line to rightmost side of map).  You can also see it at Reelection Rates of Incumbents in the U. S. House.  This graphic shows the start years of each five-congress cycle as 1983, 1993, 2003, and so forth.  The 1960s saw the Supreme Court impose strict one-person, one-vote standards for the once-a-decade redistricting, so incumbents faced a special jeopardy in electoral 1972, 1982, 1992, and 2002 of representing new territory and people while losing old ones.  There is noticeably higher departure of incumbents in 1973, 1983, and 1993 (93rd, 98th, and 103rd House).  We had reason to expect the same in 2003 (the 108th House)--but that did not happen.

    U.S. House districts must be redistricted each decade per strict Supreme Court prohibition of district malapportionment which denotes population inequality from district to district.  That's disallowed as violation of the equal protection clause of the 14th Amendment, so all districts are redrawn to equal population once Census data is available (United States congressional apportionment) except in the seven states that currently have one congressional district each.  Redistricting is normally done by each state's legislature--and sometimes is farmed out to an independent commission, or is left to the judiciary to do it.  When legislators do it they employ up to three concurrent political goals:  1) help incumbents get reelected, 2) help the state legislature's majority party gain more congressional seats, and 3) assist in creating or preserving minority representation there.  The most recent Census of 2000 produced redistricting by 2002 (and some extra in Texas through 2004, courtesy of the hyperactively partisan former Representative Tom DeLay) that will hold through the 2010 election.  The exact mix of these is richly varied, but the 50-state net impact has pointed toward decreased competition against incumbents since 2002 (Abramowitz et al., 2005; Jacobson 2008).

    The most recent redistricting was effective in 2002 after publication of Census 2000.  Incumbents fared rather well.  In the 2002 through 2006 House elections, 1204 of 1305 incumbents sought reelection, and 1157 were winners to just 47 losers (success rate = 96.01%).  The Senate, where of course district alteration is absent with its statewide elections, saw 81 of 99 seek reelection, and 71 of those were successful.  That's a senatorial success rate of 87.65%.  Were it not for voluntary departures by incumbents there would've been virtually no turnover to new members at all.  What's more, a record number of House incumbents coasted to victory without meaningful contests.  In 2002 and 2004, only 58 of some 802 incumbent-challenger match-ups were decided by fewer than 10 percentage points (Abramowitz et al. 2005).  That's 1 in every 15 that could plausibly come out differently if the stars had lined up right.  We've never before seen such one-sided incumbent dominance as the 2000 cycle has produced.

    One thing that can boost incumbents' losses is a national partisan tide (Kohut 2006, Midterm Match-Up:  Partisan Tide vs. Safe Seats - Pew Research Center).  These aren't enduring and fundamental partisan realignments, but rather are specific national reactions to performance of the "party in power" at the White House.  These sign in with noteworthy shifts in the partisan seat balance of the 435-seat lower house.  We regularly see these, in years like 1930, 1934, 1946, 1948, 1958, 1964, 1966, 1974, 1980, 1994, and 2006 (Renka, Presidents and Congresses, 1933-2010).  The 2006 midterm outwardly suggested a major change because it was a sweeping national Democratic Party victory comparable to the Republican sweep of midterm 1994.  Practically every district where both parties fielded candidates with some campaign money showed hefty jumps in the Democratic share of two-party vote.  Yet 2006 still saw only 23 House Republican incumbents defeated.  That's the 5.7 percentage point "kill rate" (cited above) against incumbents, right at the previous 1982-to-2004 average loss rate.  This was not anti-incumbency at work, as all losers were incumbent Republicans; and similarly in 1994, all 35 incumbent losers that year were Democrats.

    Probably the post-2000 Census increased use of gerrymandering prevented an even larger Republican loss in 2006.  That's because this process created more safe districts for both parties than before.  This reduces the exposure of incumbents who can lose if a year goes against their party.  It's not an ironclad guarantee of safety as the 2006 Republican losers typically had 60 percent or more of the two-party vote in 2004, yet they lost in 2006 as exit polls demonstrated that voters cared deeply about the war in Iraq and the corruption and management failures of the national party in power.

    Of course such gerrymandering cannot touch the Senate, but the 2006 national partisan tide did.  The upper house saw 6 losers out of 30 seeking reelection, all of them Republicans (United States Senate elections, 2006 - Wikipedia).  That's around a 20 percent "kill rate."  But don't make a lot from that, as this is too small a data set to shake us from concluding that the Senate has gone back to pre-1982 competitiveness.

    Something isn't quite right with this picture.  The constitutional idea since the 1913 amendment to adopt direct election of senators is "build it" (elections, that is) and "they will come" (challengers seeking to oust old ballplayers from positions in this Field of Political Dreams).  Apparently since 1982, the democratic mechanism of refreshment and change has ceased to work very well.  It's incumbent upon us to understand why.

District Design and Partisan Polarization                     Top; Next Down

    It's not simple or easy to explain why it has gotten so difficult to defeat incumbents, particularly those in the House.  The historical or pre-1982 data showed higher success at overturning them.  The postwar success rate of House incumbents ran about 90 percent, Senators only about 78 percent.  That's fairly high, but not comparable to the lofty recent rates.  What has changed to make them so hard to defeat?

    We know it's related to creative district boundary design.  This practice is commonly called gerrymandering whenever 1) a political purpose exists, and 2) the result is a strange set of district boundaries owing not to natural obstacles like ocean or mountain borders, but rather to the intelligent design of politicians.  Its most common form after the 2000 Census is the statewide "sweetheart gerrymander" where incumbents of both parties secured safer territory by shedding dangerous citizens across newly drawn boundaries.  The State of Missouri's 9 congressional districts were treated this way for 2002 with a bipartisan negotiation led by a top Republican and a top Democratic congressional district manager.  One of the best examples of this process is the Illinois 17th Congressional District, shown here:  Adam Carr's Election Archive - Downstate Illinois.  In 2004 this was the property of Lane Evans (D-Il.), and he was easily reelected in 2002 and 2004 by margins of 60% or more (Lane Evans - electoral history).  Evans in the 1990s cycle of five elections had a difficult life in a competitive district, always reelected but never by more than 55%, and always with a viable challenger who possessed enough campaign funds to make a go of it.  His district was basically up for grabs by either party.  Evans could use a break, and he got one from the State of Illinois legislature in Springfield.  The "district fairy" arrived at Evans' door, as the artful boundary lines of Illinois's 17th congressional district creatively demonstrates.  It became much bluer or more Democratic.  Not that this provoked any outrage among his neighboring congressional Republicans.  For every troublesome nest of GOP supporters ousted from the 17th, a new set of friendlies were placed into incumbent Republican terrain like the adjacent 15th, 18th and 19th C.D.'s (for example, Illinois's 18th congressional district).  Bluish got more blue, therefore reddish got more red.

    There were exceptions to this practice, but they are comparatively rare.  A leading one is Iowa with five districts drawn not by politically sympathetic state legislators, but by relatively impartial panels of jurists (Carr's Election Archive - Iowa in 2004; compare to Iowa in 2006).  These boundaries take in Democrats and Republicans alike, even honoring traditional rural county lines.  Iowa elections can be competitive, unlike the Illinois 17th across the River.  Fiorina in conclusion of Culture Wars? (2005, 214-219) has the State of Iowa rather than Illinois in mind when he recommends curbing election of partisan "wing nuts" by having relatively nonpolitical judicial commissions do the district line drawing.

     Fiorina's recommendation to farm out redistricting to impartial commissions is gaining ground in states where populist-styled referendum voting is permitted.  You can see this (circa November 2009) in Gerrymandering - Recent Steps showing that Washington, Arizona, Rhode Island, and New Jersey have moved this direction.  But it doesn't mention that California voters rejected this move in 2006 despite the urging of their popular Governor, Arnold Schwarznegger; and this despite abundant evidence that Sacramento's politicians did a classic bipartisan incumbent-protection remapping of California after the 2000 Census that produced virtually zero 2004 losses by either red R or blue D incumbents in both the statehouse and California's more than 50 Congressional Districts (United States House of Representatives elections in California, 2004).

    There are critics of the Fiorina claim that gerrymandered redistricting is the prime suspect in polarization via election of "wing nuts" on right or left.  Abramowitz et al. (2005) say that in 2002 and 2004 elections the specific or unique effect of district redesign was minimal.  But that's true in part because the 1990s saw spectacularly gerrymandered districts devoted to making that terrain safe for one party, one racial group, and one incumbent (and I recommend NOT trying lightly to separate these three things, unless you're writing a senior honors paper in political science under my careful direction).  Many of these went unchallenged in court and survived largely intact past the 2000 Census.  You can see the carryover of such district design in urban Chicago (Carr's Election Archive - Chicago with the "dumbbell" 4th C.D., property of Latino Democrat Luis Gutierrez); or view the jungle boundary lines of Los Angeles districts (See Election Archive - Los Angeles; try doing this one as a jigsaw puzzle!).  That's design.

    The analysis that minimized contribution of district redesign to incumbents' advantage has another criminal suspect that proved quite guilty.  That's partisan polarization.  See Keith Poole's Data Download Front Page for a standard measure of ideological division (called DW-NOMINATE) among Members of Congress on floor votes.  This lets us compare ideological divisions in Congress over time.  It turns out that recent partisan polarization has advanced so far that the "middle is emptied out" by the 107th House (2001-02).  (Poole doesn't show the 108th through 110th, but we already recognize that they're at least as ideologically polarized as the 107th was.)  You can read your way through earlier data from Poole's The Ideological Structure of Congressional Voting with an eye to its horizontally aligned first dimension (or dominant) ideological division.  It becomes obvious that the two parties are far apart recently, aligned against each other like enemy camps; but not that long ago, both parties sprawled across considerable ideological space and had lots of overlap.  Moderates were once comfortable and at home in either party, but now they're held suspect and liable to punishments from both--including violations of their traditional seniority rights to committee chairmanships (Renka and Ponder 2005).

    This polarization is actually quite compatible with creative gerrymandering.  For election purposes, polarization by 2001 and 2002 meant that state legislatures could reliably design revamped post-Census red/Republican districts to elect partisan warriors of one color; and concurrently do blue/Democratic districts for the other.  Furthermore, the shakeout whereby all elite conservatives are Republican and all elite liberals are Democratic has made it greatly easier for citizens to figure out which party and candidate slate to support.  Neither class of partisan incumbents is liable for many losses once districts are established with clear red or clear blue predominance.

    This isn't mere theory.  It was commonplace practice for 2002 in California and elsewhere.  In the State of Missouri, chiefs of staff for a leading House Democrat and a leading House Republican sat down together, worked out a mutually satisfactory map, and successfully presented it to the Missouri General Assembly for ratification in time for the 2002 midterm congressional elections.  District lines had to be adjusted at the margins in locales like urban and suburban St. Louis.  That predictably made the red districts redder and blue districts bluer.  The nine House incumbents looked on happily with one churlish cultural-warrior exception who was nonetheless not jeopardized in November's general election.   Incumbents both red and blue all were safe in November 2002, per United States House of Representatives elections, 2002 - Missouri.

    Thus we have given secure station to cultural warriors.  Despite the ranks of cultural ideologues being rather thin in number among the public, their numbers in the U.S. House have been proliferating.  Remember that Forum question I posed about whether getting back to God was necessary to keep America from declining?  Few of you held to that view, for it's a premise of serious cultural warriors like Patrick Buchanan rather than of typical citizens (especially if they're young).  There are far more of them in our House of Representatives than among us.  They like to rail against the Supreme Court; and some suggest ways to curb the Court's jurisdiction over cultural questions so that they may be addressed by the Congress instead.  We got a small look at that process in March 2005 with the Terri Schiavo controversy (Fiorina 2005, 157-163; also Public opinion and activism in the Terri Schiavo case - Wikipedia).  But that was deeply unpopular with most observers who paid any attention (survey compilation - Polling Report > Miscellany > Terri Schiavo).  But few if any cultural warriors in safe districts will pay for that at election time.

    The underlying trend to party orthodoxy among congressional districts usually takes the overused red-blue terminology of Republican red districts growing redder, Democratic blue ones becoming bluer.  Through the 1990s to now, there's been a geographic separation of urban Democrats from rural Republicans that, along with new computer technology and high political penalties for failure to do it, has made deliberate political drawing of partisan preserves almost a real science.  It's rare now for district to split their partisan vote, as so many southern and other districts once did back in the 1970s and 1980s.  Districts that voted Bush in 2000 and 2004 elected Republicans down the ticket; districts that voted Gore and Kerry also elected Democrats to Congress.  Exceptions came about in favor of freshman Democrats in 2006 (such as Heath Shuler of North Carolina's 11th C.D.), but they're still rare.  Members from such dangerous territory are certain to draw real opposition funded with serious money, enough to produce that modern rarity:  an authentic election contest for Congress that is worth watching closely.  That will surely happen in 2008, but the raw number of such contests will still be slight.

Starvation                         Top; Next Down

    Money is not the root of all evil or even all inequality in politics.  But in congressional contests, it is an excellent indicator of who thrives and who starves.  Modern congressional campaigns are very expensive, and those costs have escalated far beyond normal economic inflation.  Patterson (2008) correctly says those costs have roughly doubled each decade with their five elections since the 1980s (p. 305, Figure 11-2).  Money follows prospects of success quite faithfully, whether its donor be a PAC, an individual, or a political party.  All are looking for likely winners so their investments of scarce funds are not wasted.  Money is not a sufficient condition for electoral success, but it is a necessary condition.  It won't make an ugly candidate beautiful in voters' eyes; but its absence makes a beautiful one invisible.

    Even a cursory look at the 435 biennial contests among incumbents, open-seat contestants, and challengers reveals that everybody has ample money except the challengers.  Most House seat challengers exist on starvation campaign diets.  As a result, analysts point to that as a prime culprit for poor challenger fortunes.  Of course that is true, and the corrective is easy to recognize--but hard to put in place.  That corrective is to ensure public financing at adequate levels for both contestants in the duopoly-based general elections.  We have done that with national presidential elections ever since 1976, in reaction to 1972 when the incumbent Richard Nixon had a major financial advantage over challenger George McGovern.  We could do it at modest expense for congressional challengers.  But we know this:  the "marginal value in votes" of each additional campaign dollar is much greater for challengers than for incumbents.  That makes simple sense because challengers largely start out unknown and obliged to buy expensive media ads to change that; whereas incumbents start out reasonably well-known already.  Recognition by voters in the voting booth has to be bought with campaign ads.  Incumbents also know this, and accordingly are unlikely ever to willingly author campaign finance reform to give challengers a fairer shake of the money tree.  Only a massive public fuss against the status quo would shake them loose from this position.

    Then another avenue for correction might be to reduce campaign costs.  Needless to say, cost-cutting is popular with voters.  That could be done by treating television time as public property, and allotting a portion of it to public debate.  Obviously this has also been done for presidential contests (which are highly competitive).  Why not for congressional ones?  The objections to this will naturally come from television stations, which rake in substantial sums of money from escalating campaign ads.  They won't freely give away this space.  But their legal status is shaky, for law has long ago designated television air space as a public commodity to be licensed off to applicants.  By that token, a set-aside of some air space for campaigns would hardly be invasion of private prerogatives.

    The hidden objection to free television will also come from incumbents, who enjoy great competitive advantages in raising money in the current high-cost and escalating-cost political atmosphere.  But they're at a disadvantage in giving clear voice to that sentiment, since it lays bare their vested interest in keeping the election games rigged in their favor.

    Or one can reject both these things and hope for a new crop of good challengers to somehow solve the incumbent advantage all by themselves.  That could happen, of course; but I don't bet on filling inside straights.  The chief agency for recruiting better challengers would have to be the two political parties, but the financing of good candidates is largely in the hands of private parties, and the onus of failure falls very heavily on the self-starting candidates themselves.  The parties have not done very much to beat the bushes and persuade potential candidates that they can challenge and defeat incumbents.  And that's because most partisan help for races to the Hill come from Hill parties!  That is, the House Republicans and Democrats and Senate Republicans and Democrats invest heavily on congressional races; the Democratic National Committee and Republican National Committee do not.  And those four "Hill parties" quite naturally invest mostly in protecting their own incumbents. 

    So simply put:  don't go expecting miracles in the hard business of getting elected and reelected.  This system was rigged by design, and could only be unrigged the same way.  Most who did the rigging want no part of undoing their own handiwork.
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Works Cited

Abramowitz, Alan I., Brad Alexander, and Matthew Gunning.  2005.  Incumbency, Redistricting, and the Decline of Competition in U.S. House Elections.  Presented at the Annual Meeting of the Southern Political Science Association, Intercontinental Hotel, New Orleans, Louisiana, January 6-8, 2005.  URL:  http://www.emergingdemocraticmajorityweblog.com/spsa/spsa.html.

Adam Carr's Election Archive - United States of America.  undated.  URL:  psephos.adam-carr.net/countries/u/usa/congress/housemapsindex2004.shtml (for 2004 districts), psephos.adam-carr.net/countries/u/usa/congress/housemapsindex2006.shtml (for 2006 districts)

Fiorina, Morris P., with Samuel J. Abrams and Jeremy C. Pope.  2005.   Culture War?  The Myth of a Polarized America, 2d ed.  New York:  Pearson Education, Inc.

Jacobson, Gary C.  2008.  The Politics of Congressional Elections, 7th ed.  New York:  Longman Classics.

Kohut, Andrew.  2006.  Midterm Match-Up:  Partisan Tide vs. Safe Seats, February 13, 2006.  PewResearchCenter Publications.

Patterson, Thomas E.  2009.  The American Democracy, 9th ed.  New York:  McGraw Hill.

Poole, Keith.  undated.  The Ideological Structure of Congressional Voting.  URL:  http://voteview.com/ideological_maps.htm.

Renka, Russell D., and Daniel E. Ponder.  2005.  Committee Seniority Violations in the U.S. House During Republican Control since the 104th House.  Presented at the Annual Meeting of the American Political Science Association, Washington Marriott Hotel, Washington, D.C., August 30-September 3, 2005.

Renka, Russell D.  Presidents and Congresses, 1933-2010.  URL:  cstl-cla.semo.edu/renka/ui320-75/presandcongress.asp.
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Copyright©2010, Russell D. Renka