Primary election competitiveness in state government, 2021

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Last updated on August 5, 2025

Ballotpedia's 2021 state primary election competitiveness data analyzes all 225 state legislative and state executive elections that took place in 2021. This analysis provides an understanding of how competitive the year's primary elections were using metrics including the number of incumbents who did not seek re-election, the total number of contested primaries, and the number of incumbents with primary challengers. Historical comparisons are also provided for context.

Ballotpedia has published comprehensive competitiveness data from each election cycle since 2010. In 2021, this includes data from state legislative and state executive filings.

HIGHLIGHTS

As of June 2021, an average of 2.3 candidates per seat filed for election, roughly the same as every odd-year election cycle since 2015.

Of the 225 seats up for election, 8.9% were open. This was the smallest percentage of open seats since at least 2015. 20.8% of seats were open in 2019, 10.2% in 2017, and 15.7% in 2015.

Of the 205 incumbents who sought re-election, 20.0% had contested primaries, a lower rate than 2019 when 30.6% of incumbents had contested primaries, but higher than the rate in 2017 at 16.3%. In 2015, 24.6% of incumbents had contested primaries.

On this page you will find:

• Aggregate primary competitiveness data, including historical comparisons with odd-year election cycles since 2015. Click here to view the most recent even-year analysis.
• Primary competitiveness by office type

Overview

The following statistics are an aggregate of primary election competitiveness data across all states with completed filing deadlines unless otherwise noted. Corresponding data from 2019, 2017, and 2015 are provided for comparative purposes. For state-specific competitiveness data in 2021, click here.

The table below shows aggregate primary competitiveness and incumbency statistics by office from New Jersey, Virginia, and Wisconsin. You may need to move the table horizontally using the scrollbar at the bottom of the table depending on your screen size.

2021 aggregate primary competitiveness data
Office	Districts/ offices	Seats	Open seats	Candidates	Possible primaries	Contested Democratic primaries	Contested Republican primaries	Contested top-two primaries	% of contested primaries	Incumbents in contested primaries	% of incumbents in contested primaries
State executives	5	5	3	29	6	3	1	1	83.3%	1	50.0%
State legislature	180	220	17	491	332	27	17	0	13.3%	40	19.7%
Totals	185	225	20	520	338	30	18	1	14.5%	41	20.0%

2019

Kentucky, Louisiana, Mississippi, New Jersey, and Virginia held state primary elections in 2019. Click [show] on the table below to view aggregate primary competitiveness data from that year.

2019 aggregate primary competitiveness data
Office	Districts/ offices	Seats	Open seats	Candidates	Possible primaries	Contested Democratic primaries	Contested Republican primaries	Contested top-two primaries	% of contested primaries	Incumbents in contested primaries	% of incumbents in contested primaries
State executive	35	35	14	128	55	10	14	14	69.1%	14	66.7%
State legislative	498	538	105	1,091	850	67	56	92	25.3%	125	28.9%
Total	533	573	119	1,219	905	77	70	106	28.0%	139	30.6%

2017

New Jersey and Virginia held state primary elections covered by Ballotpedia in 2017. Click [show] on the table below to view aggregate primary competitiveness data from that year.

2017 aggregate primary competitiveness data
Office	Districts/ offices	Seats	Open seats	Candidates	Possible primaries	Contested Democratic primaries	Contested Republican primaries	Contested top-two primaries	% of contested primaries	Incumbents in contested primaries	% of incumbents in contested primaries
State executive	5	5	3	28	9	3	3	1	77.8%	1	50.0%
State legislative	180	220	20	472	352	33	18	0	14.5%	32	16.0%
Total	185	225	23	500	361	36	21	1	16.1%	33	16.3%

2015

Kentucky, Louisiana, Mississippi, New Jersey, and Virginia held state primary elections in 2015. Click [show] on the table below to view aggregate primary competitiveness data from that year.

2015 aggregate primary competitiveness data
Office	Districts/ offices	Seats	Open seats	Candidates	Possible primaries	Contested Democratic primaries	Contested Republican primaries	Contested top-two primaries	% of contested primaries	Incumbents in contested primaries	% of incumbents in contested primaries
State executive	24	24	9	87	41	6	11	7	58.5%	10	66.7%
State legislative	498	538	79	994	852	49	50	70	19.8%	107	23.3%
Total	522	562	88	1,081	893	55	61	77	21.6%	117	24.6%

2013

New Jersey, Virginia, and Wisconsin held state primary elections in 2013. Click [show] on the table below to view aggregate primary competitiveness data from that year.

2013 aggregate primary competitiveness data
Office	Districts/ offices	Seats	Open seats	Candidates	Possible primaries	Contested Democratic primaries	Contested Republican primaries	Contested top-two primaries	% of contested primaries	Incumbents in contested primaries	% of incumbents in contested primaries
State executive	5	5	3	14	6	3	1	0	66.7%	1	50.0%
State legislative	180	220	15	428	360	12	20	0	8.9%	24	11.7%
Total	185	225	18	442	366	15	21	0	9.8%	25	12.1%

2011

Kentucky, Louisiana, Mississippi, New Jersey, and Virginia held state primary elections in 2011. Click [show] on the table below to view aggregate primary competitiveness data from that year.

2011 aggregate primary competitiveness data
Office	Districts/ offices	Seats	Open seats	Candidates	Possible primaries	Contested Democratic primaries	Contested Republican primaries	Contested top-two primaries	% of contested primaries	Incumbents in contested primaries	% of incumbents in contested primaries
State executive	24	24	7	81	41	6	11	5	53.7%	8	47.1%
State legislative	538	578	98	1,112	874	48	65	81	22.2%	104	21.4%
Total	562	602	105	1,193	915	54	76	86	23.6%	112	22.3%

Breakdown by office

The tables below show primary competitiveness statistics overall and broken down by office type. Figures are shown as percentages with overall figures shown first. Click [show] on the bars beneath the table to view statistics by office type.

Comparison of overall primary competitiveness percentages, 2011-2021
	2011	2013	2015	2017	2019	2021	Average
Open seats (%)	17.4%	8.0%	15.7%	10.2%	20.8%	8.9%	13.5%
Total primaries (%)	23.6%	9.8%	21.6%	16.1%	28.0%	14.5%	18.9%
Inc. in contested primaries (%)	22.3%	12.1%	24.6%	16.3%	30.6%	20.0%	21.0%

State executive
	2011	2013	2015	2017	2019	2021	Average
Open seats (%)	29.2%	60.0%	37.5%	60.0%	40.0%	60.0%	47.8%
Total primaries (%)	53.7%	66.7%	58.5%	77.8%	69.1%	83.3%	68.2%
Inc. in contested primaries (%)	47.1%	50.0%	66.7%	50.0%	66.7%	50.0%	55.1%

State legislative
	2011	2013	2015	2017	2019	2021	Average
Open seats (%)	17.0%	6.8%	14.7%	9.1%	19.5%	7.7%	12.5%
Total primaries (%)	22.2%	8.9%	19.8%	14.5%	25.3%	13.3%	17.3%
Inc. in contested primaries (%)	21.4%	11.7%	23.3%	16.0%	28.9%	19.7%	20.2%

The charts below show primary competitiveness statistics broken down by office type. The figures shown are total numbers. This analysis uses the following definitions:

• Total candidates: the total number of major party candidates running in primary elections.
• Total seats: the total number of seats or offices up for election with the possibility of a primary election.
• Open seats: the total number of seats, out of the total seats figure, where the incumbent did not file to run for re-election or filed to run for re-election but withdrew before the primary filing deadline.
• Incumbents contested: the total number of incumbents in contested primaries.
• Democratic/Republican/Top-two primaries: the total number of these types of primaries where at least one candidate could have failed to advance to the general election.
• Total primaries: a combination of all Democratic, Republican, and top-two primaries where at least one candidate could have failed to advance to the general election.