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American elections come in two flavors: those with an incumbent running and those without. The difference between these two types of races shapes everything from who runs to who wins, and ultimately, how responsive our government is to voters.
When a sitting officeholder seeks re-election, they bring a powerful set of built-in advantages that can make the race feel predetermined. These “incumbency advantages” are so strong that over 90% of House members who run for re-election win.
But when there’s no incumbent on the ballot—what’s called an “open seat”—the playing field levels dramatically, creating some of the most competitive and unpredictable contests in politics.
This fundamental divide affects who gets to serve, what policies get passed, and whether elected officials stay connected to the people they represent.
The Landscape: Who’s Running and Why It Matters
What Makes Someone an Incumbent
An incumbent is simply the person currently holding the office that’s up for election. If a senator is finishing their six-year term and that Senate seat is on the ballot, they’re the incumbent—regardless of whether they’re actually running again.
But there are some wrinkles. Ballotpedia defines incumbency by legislative chamber, not specific district. So if a state representative from District 1 runs for re-election in District 2 due to redistricting, they’re still considered an incumbent because they’re staying in the same chamber. But if that same representative runs for the state senate, they’re not an incumbent in that race since it’s a different chamber entirely.
These distinctions matter when interpreting election statistics and understanding what “incumbency” really means in different contexts.
When Seats Go Empty
An open seat election happens when no incumbent appears on the ballot for a specific office. Without an incumbent’s built-in advantages, these races create entirely different competitive dynamics.
Several things can create open seats:
Voluntary departures are the most common. Incumbents retire, resign, or choose not to seek re-election. Sometimes they run for a different office instead.
Death in office necessitates an election, often starting with a special election followed by a regular election for the full term.
Term limits automatically create open seats. In 2022 state legislative elections, 252 legislators across the country were term-limited, making their seats open contests and accounting for 4% of all seats up for election that year.
Redistricting can create new districts with no incumbent, or significantly alter existing districts in ways that discourage incumbents from running.
Scandals or political fallout sometimes force incumbents to withdraw, though this is less common.
The reason a seat becomes open significantly influences the election that follows. A popular incumbent’s voluntary retirement might still benefit their party in recruiting a strong successor. Term limits create predictable vacancies that allow longer-term strategic planning. Scandals can create particularly volatile races if the opposing party can capitalize on voter anger.
The Incumbency Advantage: Built-In Benefits
The incumbency advantage refers to the collection of benefits that sitting officeholders possess when seeking re-election. These advantages are substantial and measurable—they’re not just theoretical concepts but real electoral forces that significantly boost an incumbent’s chances of winning.
The Numbers Don’t Lie
Re-election statistics across all levels of government show just how powerful incumbency can be.
In Congress, the numbers are striking. During the 2018 elections, 91% of House incumbents and 84% of Senate incumbents who sought re-election won. Looking at 2024 elections, 97% of congressional incumbents who ran were re-elected. House members have won re-election more than 90% of the time throughout the modern political era since 1945.
State legislatures show similar patterns. Incumbency win rates typically hover around 95% or higher. A Ballotpedia analysis covering 1972 to 2014 found that incumbent win rates never fell below 88% during that entire period.
But raw win rates only tell part of the story. Political scientists also measure the specific electoral boost incumbents receive just from holding office—the extra percentage points they gain purely from being the incumbent.
For House members, this advantage was about 2 percentage points in the 1950s, climbed to 10 percentage points in the 1980s and 1990s, then settled back to 2-3 percentage points in recent cycles. A 2024 analysis by Princeton researchers calculated the average net incumbency advantage at 2.58 percentage points.
State legislative incumbents typically see about a 5.3 percentage point boost from incumbency, according to research using quasi-experimental methods.
How the Advantage Works
The incumbency advantage isn’t accidental—it’s built from several powerful tools and favorable conditions that come with holding office.
Name recognition is fundamental. Having already won an election and served in office, incumbents are far more familiar to voters than their opponents. In many elections, particularly for state legislative or local offices, voters may not closely follow campaigns or candidates’ positions. Simply recognizing a name on the ballot can be decisive, often leading voters to choose the familiar incumbent.
Campaign finance superiority might be the most significant advantage. Incumbents find it much easier to raise money for several reasons: they have established donor networks from previous campaigns, they’re seen as “proven winners” that donors want to back, and they interact with interest groups through their official duties.
The financial gaps are enormous. OpenSecrets data for the 2023-2024 cycle shows Senate incumbents raised an average of $31.2 million compared to challengers’ $2.8 million. House incumbents averaged $3.0 million while challengers managed just $467,000.
Government resources provide indirect campaign benefits. The franking privilege allows members of Congress to send official mail to constituents at taxpayer expense. While regulated to prevent overt campaigning, this free communication maintains visibility and name recognition. Incumbents also have official staff paid by the government who perform constituent services, strengthening bonds with voters.
Media access generally favors incumbents who receive coverage for their official activities and policy positions. However, research suggests this advantage may be more limited than commonly believed, especially in competitive races.
Constituent services create personal connections with voters. When incumbents and their staff help people navigate federal agencies—solving Social Security problems, veterans’ issues, or immigration cases—they build goodwill and earn what political scientists call a “personal vote.”
The sophomore surge shows how quickly incumbency benefits kick in. First-term representatives typically receive a higher vote percentage in their first re-election campaign compared to their initial election, often as much as 10 percentage points more.
Deterring quality challengers might be the most subtle but powerful effect. Well-qualified potential candidates often decide not to run against strong incumbents, calculating that their chances are too low and the costs too high. This “scare-off effect” means incumbents often face weaker, less-funded opponents, further improving their re-election odds.
The Reinforcing Cycle
These advantages don’t work in isolation—they reinforce each other. Superior fundraising enables more campaign activities, which generates more media coverage and name recognition. Successful constituent services enhance an incumbent’s reputation, making it easier to attract donations from people who see them as effective. Large campaign war chests signal strength and discourage strong challengers.
However, incumbency isn’t invincible. An “anti-incumbency factor” can emerge when incumbents perform poorly, face scandals, or when voters simply want change. Individual performance varies significantly among incumbents, and some even show negative advantages—they perform worse than a generic candidate from their party would in that district.
| Table 1: U.S. Congressional Incumbent Re-election Rates (Selected Recent Cycles) |
|---|
| Year |
| 2024 |
| 2022 |
| 2022 |
| 2020 |
| 2020 |
| 2018 |
| 2018 |
When Seats Open Up: A Different Game
Open seat elections fundamentally alter the electoral landscape. Without an incumbent’s advantages, these contests become significantly more competitive and unpredictable.
The Competition Heats Up
Political scientists Ronald Keith Gaddie and Charles S. Bullock III described open seats as “where the action is” in their influential research on House elections. These races feature vigorous competition both between parties and within party primaries as candidates compete for nominations.
The numbers back this up. In 2022, 23.8% of all state legislative seats were open, guaranteeing a significant influx of newcomers to state legislatures across the country.
Voters Compare Candidates Directly
When an incumbent is running, elections often become what political analyst Guy Molyneux called “fundamentally a referendum on the incumbent.” Voters primarily evaluate the officeholder’s record and performance. Only if they decide to “fire” the incumbent do they seriously consider the challenger.
Open seat elections shift this dynamic completely. With no incumbent record to judge, voters must directly compare candidates’ qualifications, policy positions, and personal characteristics. The election becomes less about keeping or removing a known quantity and more about selecting the best new representative from a field of contenders.
Better Candidates Enter the Race
Open seats serve as the main “gateway into Congress” and other legislative bodies. Research shows that roughly two-thirds of House members initially entered by winning an open seat. Without an incumbent to overcome, open seats attract larger fields of candidates, often including higher-quality contenders with political experience, strong fundraising potential, or significant community standing.
These candidates might have been reluctant to launch expensive, difficult challenges against entrenched incumbents. Research on candidate quality shows that open-seat candidates possess higher “valence”—non-policy attributes like competence and general appeal—than those who challenge incumbents directly.
Primary elections in open seats, particularly for the party with an advantage in “safe” districts, become especially important for selecting strong nominees since the primary winner often becomes the general election favorite.
Money Flows Differently
Campaign spending in open seats is substantial, though patterns differ from incumbent races. While open seat candidates typically raise less than incumbents, they generally raise more than challengers facing incumbents.
2023-2024 OpenSecrets data shows candidates for open Senate seats raised an average of $5.25 million, while open House seat candidates averaged $745,399. This falls between incumbent totals and challenger amounts, reflecting the competitive but not overwhelming nature of these races.
Research on House open-seat contests from 1990-2004 found that election outcomes are highly sensitive to campaign spending ratios between major-party candidates. This has led some strategists to assert that “open seats are bought, not won,” though this oversimplifies the role of spending in these complex races.
Strategic Calculations
Open seats trigger strategic thinking by potential candidates and political parties. Ambitious politicians often wait for open seats rather than challenging incumbents, recognizing the much better odds of success. Parties concentrate significant resources on open seat contests since they represent the best opportunities to gain new seats or defend vulnerable ones.
Open seats are also the primary mechanism for legislative turnover. Since incumbents win re-election at such high rates, open seats represent the main pathway for new people and new perspectives to enter legislative bodies.
Two Different Electoral Worlds
The presence or absence of an incumbent creates two distinct electoral environments with different strategies, media coverage, and voter behavior.
Campaign Strategies
Incumbent campaigns typically focus on reinforcing the officeholder’s record, highlighting achievements, and leveraging the prestige of their current position. Secure incumbents might adopt a “rose garden” strategy, concentrating on official duties to appear above politics. Threatened incumbents often work aggressively to define and discredit their challengers.
Challengers face a two-part task: building name recognition while giving voters compelling reasons to replace a known quantity.
Open seat campaigns operate under different rules. All candidates must build name recognition from scratch and differentiate themselves from other contenders who are also relatively unknown. Campaign messaging focuses more on future vision, new ideas, personal biography, and endorsements rather than legislative records.
Media Coverage
Media narratives frame these election types differently. Incumbent races are often portrayed as referenda on the officeholder’s performance or linked to national political trends. Incumbents may receive more overall coverage for their official duties, though research suggests this advantage can be marginal in competitive races.
Open seat elections generate “horse race” coverage focusing on polling, fundraising, and candidate personalities. Media often emphasize the potential for seats to “flip” between parties, making these races key battlegrounds for legislative control.
Voter Decision-Making
Voters process information and make decisions differently in these two contexts.
In incumbent races, voters often rely on established cues: party identification, name recognition, and evaluations of past performance. If the incumbent is well-known and the race seems uncompetitive, voters might engage in less intensive information gathering.
Open seat elections typically prompt more active voter information-seeking. Without an incumbent’s track record, voters need to learn about multiple new candidates and may seek detailed information to compare policy positions, qualifications, and backgrounds.
The increased number of candidates in open seats can create higher information loads for voters, though competitive campaigns usually generate more news coverage and communications, providing voters with more information from various sources.
| Table 2: Comparing Elections: Incumbent-Led vs. Open Seat |
|---|
| Feature |
| Key Voter Question |
| Campaign Focus |
| Media Narrative |
| Candidate Pool |
| Competitiveness |
| Voter Information |
| Fundraising |
The Statistical Reality
Hard data on re-election rates, electoral advantages, and campaign finance reveals the true scope of these electoral differences.
Re-election Success Rates
Federal Level: House incumbents enjoy exceptionally high re-election rates. The Brookings Institution’s “Vital Statistics on Congress” shows that from 1946 to 2016, House incumbent success rates rarely dropped below 80% and often exceeded 90%, reaching 98.3% in both 1988 and 1998.
Senate incumbents also succeed at high rates, though with more variation. Over the past 50 years, more than 80% of senators seeking re-election have won.
State Legislatures: Incumbency proves equally powerful at the state level. Re-election rates typically hover around 95% or higher. Ballotpedia’s analysis covering 1972 to 2014 found that incumbent win rates never fell below 88% during that entire period.
Measuring the Advantage
Beyond win rates, political scientists quantify the specific electoral boost incumbents receive just from holding office, typically measured in vote share percentage points.
U.S. House: This advantage has fluctuated significantly. It was roughly 2 percentage points in the 1950s, rose to about 10 percentage points in the 1980s and 1990s, then settled back to 2-3 percentage points in recent decades. Princeton University researchers calculated an average net incumbency advantage of 2.58 percentage points in 2024.
U.S. Senate: Academic estimates place the Senate incumbency advantage in the range of 5-6 percentage points in some studies, with earlier research suggesting 8-10 percentage points.
State Legislatures: Quasi-experimental research estimates that state legislative incumbency provides a 5.3 percentage point increase in vote share.
The decline in measured advantage from the 1980s/90s peak is significant. While incumbents still win at very high rates, the degree of their advantage purely from holding office may be changing. This could suggest that in an era of heightened polarization, party affiliation is becoming more dominant in voter choice, potentially making incumbents more reliant on their district’s partisan makeup.
Open Seat Impact
Open seats play a crucial role in electoral dynamics and legislative change.
Frequency: In 2022 state legislative elections, 23.8% of all seats (1,492 out of 6,278) were open seats. This was the largest number and percentage observed in six election cycles, marking a 70% increase from 2020.
Competitiveness: Open seats are inherently more competitive and guarantee newcomer elections. They’re often where shifts in party control occur and serve as key indicators of overall election cycle competitiveness.
Campaign Finance Gaps
Financial disparities between candidate types are stark, as shown by 2023-2024 OpenSecrets data:
| Table 3: Campaign Fundraising: Incumbents vs. Challengers vs. Open Seats (2023-2024) |
|---|
| Chamber |
| Senate |
| Senate |
| Senate |
| House |
| House |
| House |
These figures highlight the vast financial advantages incumbents hold over challengers, while open seat candidates fall somewhere in between—competitive but not dominant.
When Advantage Becomes Disadvantage
Despite powerful advantages, incumbency doesn’t guarantee victory. An “anti-incumbency factor” can emerge under certain conditions:
- Poor performance perceptions
- Scandal or controversy
- Strong desire for change after long tenure
- Negative economic conditions affecting voters
- Strong national political tides against the incumbent’s party
Recent examples include investigations into Rep. Matt Gaetz (FL-01) being linked to an estimated incumbency disadvantage of nearly 7 percentage points in 2024 analysis.
Beyond Election Day: Broader Consequences
The dynamics of incumbent versus open seat elections have profound effects on governance, representation, and democratic responsiveness.
Legislative Responsiveness
Strong incumbency advantages can potentially reduce pressure on legislators to be highly responsive to their full range of constituents. If re-election seems probable regardless of specific policy positions, incentives for broad coalition-building or appealing to median voters might diminish.
However, this relationship is complex. While general incumbent safety might reduce day-to-day responsiveness on some issues, the potential for anti-incumbency factors—scandal, perceived neglect, major policy errors—serves as an ongoing check on behavior.
Policy Innovation and Polarization
Reduced electoral competition can contribute to political polarization. Incumbents in “safe seats” may face more pressure from partisan primary voters than general election opponents, leading them to adopt more ideologically extreme positions with less incentive for bipartisan compromise.
Open seats, by guaranteeing new legislators, can serve as conduits for policy innovation. New members may bring fresh perspectives, be less tied to established norms or interest groups, and show greater willingness to champion novel solutions.
This creates a fundamental trade-off: experience from incumbency can be valuable for effective governance, but it can also lead to legislative inertia and resistance to change.
Barriers to Representation
Incumbency advantages create significant barriers for new and diverse candidates. Aspiring politicians from historically underrepresented groups—women, racial and ethnic minorities, younger individuals—may find it exceptionally difficult to overcome established incumbents’ political and financial advantages.
Open seats provide the most promising opportunities for increasing legislative diversity. Research on term limits (which create steady streams of open seats) shows interesting patterns:
Minority Representation: Racial and ethnic minorities generally gained seats when term limits created open seats. This happened both because minority incumbents were replaced by other minorities in majority-minority districts and because minorities captured some previously white-held seats.
Women’s Representation: The impact on women’s representation was more mixed, sometimes showing initial decreases in specific term-limited seats but overall stability or slight increases as women made gains in other types of races.
Broader Impact: Open seats act as crucial opportunities for demographic and ideological shifts in legislatures, allowing more rapid reflection of societal changes than systems dominated by long-serving incumbents.
Money and Influence
The substantial financial advantages of incumbents and large sums in competitive open seats raise concerns about money’s influence in politics. When incumbents amass huge war chests that deter challengers, or when open seats become multi-million dollar contests, questions arise about who funds these campaigns and what influence they might expect.
The Brennan Center for Justice has documented connections between money in politics and incumbency strength, arguing that high incumbent re-election rates are partly fueled by campaign finance systems favoring those already in power.
This creates a fundamental tension: while fundraising is necessary for modern campaigns, its dominance in determining electoral viability can potentially undermine democratic principles of equal access and representation.
The Paradox of Stability and Change
American elections reveal a striking paradox. While voters consistently express dissatisfaction with Congress as an institution—approval ratings often hover around 20%—they regularly re-elect their own representatives at rates exceeding 90%.
This suggests that many voters distinguish between their personal representative and Congress as a whole. They may view their incumbent favorably due to personal service, effective communication, or local benefits, while disapproving of the institution’s overall performance.
The implications extend beyond individual races. High incumbent re-election rates combined with periodic waves of open seats create a system that balances stability with opportunities for change. Experienced legislators provide institutional memory and policy expertise, while open seats allow for periodic renewal and the introduction of new perspectives.
Understanding this balance is crucial for citizens seeking to make sense of American democracy. Elections with incumbents and open seat contests aren’t just different types of races—they’re different mechanisms for democratic representation, each with distinct advantages and challenges.
The system’s health depends partly on maintaining this balance. Too much incumbency advantage could lead to unresponsive government and barriers to representation. Too much turnover could result in inexperienced legislatures lacking institutional knowledge.
As redistricting, campaign finance rules, and political polarization continue evolving, the dynamics between incumbent and open seat elections will likely shift as well. But the fundamental distinction—between elections that primarily judge existing officeholders and those that select new representatives—will remain central to American democratic governance.
The next time you see an election featuring a long-serving incumbent, or notice an open seat race generating unusual attention and spending, you’ll understand why. These aren’t just different types of political contests—they’re different expressions of democratic choice, each shaping not just who wins, but how our government works and whom it serves.
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