Margin of victory analysis for the 2025 state legislative elections

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After all states release final certified results, this page will analyze the electoral margins of victory for state legislative seats up for election in 2025. A margin of victory is the difference between the share of votes cast for the winning candidate and the second-place candidate in an election.

The analysis will show the average margin of victory in each state legislative upper chamber and lower chamber, breakdown margins of victory in each chamber by partisan affiliation, and list the state legislative seats that were won by fewer than 10 percentage points and fewer than 0.5 percentage points.

Click here to read from the 2023 analysis. Click here to read from the 2021 analysis.

Analysis for 2023

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.

HIGHLIGHTS

Major-party candidates won 56 seats by margins of 10% or less; Democrats won 20, and Republicans won 36.

The average margin of victory was 29.2% for Democrats and 28.4% for Republicans.

The chamber with the smallest average margin of victory in 2023 was the New Jersey General Assembly (14.7%), while the chamber with the largest average margin of victory was the Mississippi House of Representatives (47.2%).

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.

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
Louisiana State Senate	39	33.2%
Mississippi State Senate	52	36.6%
New Jersey State Senate	40	31.6%
Virginia State Senate	40	25.3%

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
Louisiana House of Representatives	105	29.9%
Mississippi House of Representatives	122	47.2%
New Jersey General Assembly^[1]	80	14.7%
Virginia House of Delegates	100	24.9%

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	Seats won by unopposed Democrats	Average margin of victory for Democrats	Seats won by Republicans	Seats won by Republicans by margins of 10% or less	Seats won by unopposed Republicans	Average margin of victory for Republicans	Seats won by independent and minor party candidates
Louisiana House of Representatives	105	32	3	17	27.8%	73	4	31	30.6%	0
Louisiana State Senate	39	11	0	8	36.3%	28	3	12	32.6%	0
Mississippi House of Representatives	122	41	0	32	48.6%	79	0	59	47.8%	2
Mississippi State Senate	52	16	0	11	22.9%	36	0	27	44.2%	0
New Jersey General Assembly^[1]	80	27	7	1	17.9%	13	8	0	8.2%	0
New Jersey State Senate	40	25	2	1	37.9%	15	5	0	21.4%	0
Virginia House of Delegates	100	51	5	18	28.1%	49	11	14	22.0%	0
Virginia State Senate	40	21	3	2	27.9%	19	5	3	22.1%	0
Total	578	224	20	90	29.2%	312	36	146	28.4%	2

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	0.18%	198
Virginia House of Delegates District 82	Kim Taylor	Kimberly Adams	0.27%	78

Click here to read the full 2023 analysis.

Analysis for 2021

On November 2, 2021, three of the nation's 99 state legislative chambers held regularly-scheduled elections for 220 seats, meaning that 2.9% of all state legislative seats were up for election.

Republicans won a majority in the Virginia House of Delegates, while Democrats held their majorities in the New Jersey General Assembly and the New Jersey State Senate. The change in Virginia broke the state's Democratic state government trifecta and resulted in a divided government.

Across all 220 seats up for election, the average margin of victory was 23.6%. 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.

HIGHLIGHTS

Major-party candidates won 46 seats by margins of 10% or less; 24 of those seats were won by Democrats and 22 by Republicans.

The average margin of victory was 25.7% for Democrats and 21.2% for Republicans.

The chamber with the smallest average margin of victory in 2021 was the New Jersey General Assembly (13.0%), followed by the New Jersey State Senate (26.1%) and the Virginia House of Delegates (27.0%).