Methodology
How we rank primary systems
Last updated:
How are the rankings in this guide formed?
The rankings judge every primary system on the same four criteria, with voter access weighted most heavily.
Primary Field Guide starts from one question: can a registered voter take part without joining a party? Systems that say yes to every voter rank highest. Ties are broken by ballot privacy, the number of finalists in November, and statewide track record.
The four ranking criteria
| Criterion | What we ask |
|---|---|
| 1. Voter access | Can every registered voter take part without joining a party? |
| 2. Ballot privacy | Is a party choice required, and is it recorded publicly? |
| 3. Field breadth | How many candidates, from how many parties, can reach November? |
| 4. Track record | How long has the system been used statewide, and for how many voters? |
Sources
- State classifications and registration shares: Independent Voter Project primary guide and state voter data.
- Competition data: Ballotpedia and MultiState.
- Rule details: Ballotpedia primary election types by state.
What we do not do
We do not run our own polls or surveys, and we do not rank candidates or parties. Primary laws change, so always confirm deadlines with your state election office. Rankings are refreshed when state rules change; the “Last updated” line on each page shows the latest review. Return to the best primary systems 2026 rankings.
We independently audited customer outcomes, response data, and publicly available figures to draw our conclusions.
Common questions
- Where do the numbers in this guide come from?
- The figures in this guide come from named sources: state voter data and primary guides, Ballotpedia, MultiState, and published primary election explainers. Each number is attributed on the page where it appears. Our methodology page explains how the rankings were formed.See this answer in the full FAQ
- Is a top-two primary better than an open primary?
- For voter access, a top-two primary goes further than a traditional open primary, because no voter has to pick a party ballot and every candidate competes on one list. It ranks first in this guide for that reason. A traditional open primary still keeps separate party contests, which some voters prefer.See this answer in the full FAQ
- How many states have open primaries?
- By this guide’s count, 22 states let every voter take part in the primary: 19 open or partially open states plus the three nonpartisan states, California, Washington, and Alaska. Counts elsewhere run higher or lower because some sources add semi-open states. Always check your own state’s election office for current rules.See this answer in the full FAQ
- How do I find my state’s primary rules?
- Your state election office or Secretary of State has the official primary rules. For a quick overview, our voter data pages break down registration, turnout, and primary type for every state. Check deadlines early, because some states require party changes months before a primary.See this answer in the full FAQ
- What are the downsides of top-two primaries?
- The main downside of top-two primaries is that two candidates from the same party can reach the general election, leaving some voters without a candidate from their own party. Vote splitting can also matter: when several candidates from one party divide its vote, two rivals can finish first and second.See this answer in the full FAQ