Margin of victory analysis for the 2023 state legislative elections
In November 2023, eight of the nation's 99 state legislative chambers held regularly-scheduled elections for 578 seats, meaning that 7.8% of all state legislative seats were up for election.
Democrats won a majority in the Virginia House of Delegates while holding their majorities in the Virginia State Senate, New Jersey General Assembly, and New Jersey State Senate. Republicans held their majorities in the Mississippi House of Representatives, Mississippi State Senate, Louisiana House of Representatives, and Louisiana State Senate. The change in Virginia did not affect the state's status as a divided government.
Across all 578 seats up for election, the average margin of victory was 28.7%. An electoral margin of victory (MOV) is the difference between the share of votes cast for the winning candidate and the second-place candidate in an election. Only races with more than one candidate were included in this average.
2023's average margin of victory of 28.7% was the highest of the last three odd-year elections, and it was higher than any average from the last three even-year elections. The average state legislative margin of victory was 23.6% in 2021 and 26.0% in 2019. The average was 27.7% in 2022, 27.0% in 2022, and 25.8% in 2018.
Of the 578 state legislative seats up for election in 2023, 9.7% (56 seats) were decided by a margin of victory of 10% or less. This was the lowest of the past three odd-year election cycles, as well the lowest of all cycles since Ballotpedia began analyzing data in 2019. The number of seats decided by a margin of victory of 10% or less was 14.0% in 2022, 21.0% in 2021, 16.2% in 2020, and 10.8% in 2019.
Of the 56 state legislative races decided by a margin of victory of 10% or less in 2023, Democrats won 20 (35.7%) and Republicans won 36 (64.3%). This is the lowest percentage of races decided by a margin of 10% or less that Democrats won for the previous five elections, and it is the highest percentage of races decided by a margin of 10% or less that Republicans won for the previous five elections.
On this page, you will find an overview of average margins of victory by chambers and size of the margin, including:
- Upper chamber average margins of victory
- Lower chamber average margins of victory
- Election results by chamber
- Races decided by 10% or less
- Races decided by 0.5% or less
- Historical margins of victory
To learn more about margins of victory in the previous odd-year state legislative elections (2021), click here. To read our margin of victory analysis for U.S. Congress in the previous even-year elections (2022), click here.
Margin of victory
The margin of victory is the difference between the vote share received by a winning candidate and the runner-up. For example, if Candidate A wins an election with 55 percent of the vote and Candidate B, the second-place finisher, wins 45 percent of the vote, the winner's margin of victory is 10 percent. In chambers with multimember districts, the margin of victory is calculated as the difference between the winning candidate with the fewest votes and the losing candidate with the most votes. Margins of victory can be used to measure electoral competitiveness, political party or candidate strength, and, indirectly, the popularity of a particular policy or set of policies.
Upper chamber average margins of victory
The table below shows the number of seats up for election and the average margin of victory in each state legislative upper chamber.
| Average MOV for state legislative upper chamber elections, 2023 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Chamber | Seats up for election | Average margin of victory | ||||||||
Lower chamber average margins of victory
The table below shows the number of seats up for election and the average margin of victory in each state legislative lower chamber.
| Average MOV for state legislative lower chamber elections, 2023 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Chamber | Seats up for election | Average margin of victory | ||||||||
Election results by chamber
The chart below displays the breakdown of races by the winner's partisan affiliation and margin of victory for each state legislative chamber with single-member districts which held elections in 2023. A darker shade of red or blue indicates a larger margin for that party.
The table below displays how many seats were up for election in each chamber and how many seats each party won. It also includes a breakdown of how many seats Democrats and Republicans won by 10% or less and without opposition in each chamber, as well as the average margin of victory for each party. Click on a particular header to sort the table.
| Average MOV for state legislative elections, 2023 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Chamber | Seats up for election |  Seats won by Democrats
|
Seats won by Democrats by margins of 10% or less
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Seats won by unopposed Democrats
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Average margin of victory for Democrats
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 Seats won by Republicans
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Seats won by Republicans by margins of 10% or less
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Seats won by unopposed Republicans
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Average margin of victory for Republicans
|
 Seats won by independent and minor party candidates
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| Louisiana House of Representatives | ||||||||||
| Louisiana State Senate | ||||||||||
| Mississippi House of Representatives | ||||||||||
| Mississippi State Senate | ||||||||||
| New Jersey General Assembly[1] | ||||||||||
| New Jersey State Senate | ||||||||||
| Virginia House of Delegates | ||||||||||
| Virginia State Senate | ||||||||||
| Total | ||||||||||
State legislative races decided by 10% or less
In 2023, there were 56 races decided by margins of 10% or less. The map below shows the percentage of races in each state decided by margins of 10% or less.
State legislative races decided by 0.5% or less
In 2023, there were two races decided by margins of 0.5% or smaller.
| State legislative races decided by 0.5% or less, 2023 | ||||
|---|---|---|---|---|
| District | Winner | Runner-up | Margin (%) | Margin (number of votes) |
| New Jersey General Assembly District 8 | Andrea Katz |
Anthony Angelozzi |
||
| Virginia House of Delegates District 82 | Kim Taylor |
Kimberly Adams |
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Historical margins of victory
The table below shows the number of seats up for election and the average margin of victory for all regularly-scheduled state legislative elections since 2018.
| Average MOV for state legislative elections, 2018-2023 | ||
|---|---|---|
| Year | Seats up for election | Average margin of victory |
See also
- State legislative elections, 2023
- State legislative special elections, 2023
- Ballotpedia's Election Analysis Hub, 2023
- Trends in the margins of victory for incumbents of three or more terms, 2018-2024
Footnotes
- ↑ 1.0 1.1 For the purposes of this study, the margin of victory was calculated by comparing the winner with the least votes to the loser of the opposite party with the most votes. Therefore, the numbers will total up to half the seats won for each party since we can only compare MoV for one of the two seats in each district.
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