By the numbers
Primary election statistics
Last updated:
In 2024, 87% of U.S. congressional races were effectively decided in primary elections.
Each figure links to the study it comes from.
How many elections are decided in the primary?
Most of them. 87% of 2024 congressional races were decided in the primary, and only 7% of voting-age Americans voted in those decisive contests. For most seats, the primary is the real election.
Who picks the winners
39% vs 11%
Independents' share of the voting-age population vs their share of decisive primary voters.
Source: Unite America Institute
47% vs 11%
Moderates' share of voting-age Americans vs their share of decisive primary voters.
Source: Unite America Institute
63M
Americans registered independent or unaffiliated, 28.9% of all registered voters.
Source: Independent Voter Project
2026 primary turnout
23.3%
National primary turnout in the 2026 midterm cycle, still rising in midterm years.
Source: Bipartisan Policy Center
12 states
Met a 30% turnout goal, including all three nonpartisan primary states: Alaska, California, and Washington.
Source: Bipartisan Policy Center
How competitive primaries are
25.5%
Share of the 5,613 incumbents filing for re-election who faced a contested 2026 primary.
Source: Ballotpedia
3.4%
State legislators seeking re-election who lost in 2026 (174 of 5,111), above the 2.9% average since 2010.
Source: MultiState
32.5%
State legislative seats on track to be uncontested by one major party in 2026, down from a 38.0% average.
Source: MultiState
A historical note on turnout
Turnout is shaped by many factors. The Wikipedia article on open primaries in the United States notes one case where primary turnout fell from 74.6% in 1978 to 42.2% in 2006 after a switch to open primaries, while cautioning that other factors may explain the drop. The 2026 data above shows the most open systems, nonpartisan single-ballot primaries, now among the highest-turnout states.
Keep reading
Start with open primaries
The first step is supporting open primaries for every voter. Next, see how More Choice Voting builds on them.
Common questions
See all 44 answersHow many elections are decided in the primary?
In 2024, 87% of U.S. congressional races were effectively decided in primary elections. Only 7% of voting-age Americans cast ballots in those decisive primaries. When one party dominates a district, the primary winner almost always wins the seat in November.
What was primary turnout in 2026?
National primary turnout reached 23.3% in the 2026 midterm cycle and continues to rise in midterm years. Twelve states met a 30% turnout goal, and only two, Oregon and California, reached 35%. Turnout in primaries remains far below general election turnout.
How many voters are registered independent?
About 63 million Americans are registered independent or unaffiliated, 28.9% of roughly 218.3 million registered voters. That is nearly as many as all registered Republicans, about 69.6 million, and makes independents one of the largest voter groups in the country.
How many primaries are actually contested?
Only 22.1% of all possible primaries in 2026 were contested. Of the 5,613 incumbents who filed for re-election, 25.5% faced a contested primary, close to the 25.6% average of the three prior cycles. Many voters therefore see no real choice in their primary at all.
How many incumbents lost primaries in 2026?
In 2026, 3.4% of sitting state legislators who sought re-election lost, 174 of 5,111, above the 2.9% average for the same 49 states since 2010. Because many seats are safe for one party, a primary loss is often the only realistic way an incumbent leaves office.
Do open primaries increase turnout?
States with the widest primary access post some of the strongest turnout. All three nonpartisan primary states (Alaska, California, and Washington) were among the 12 states that reached 30% primary turnout in the 2026 midterms. Oregon, a closed state, also cleared that mark, so other factors matter too.