This election season there has been some discussion of open versus closed primary elections, with a movement among conservative Republicans in favor of closed primaries and among progressive Democrats (notably Sanders supporters) for open ones. This got me curious about just who is allowed to vote in primaries in various states.

It turns out that there are basically four kinds of party primaries in the U.S.:

Closed: Only those who have registered in advance as affiliated with the party in question are allowed to vote in the party’s primary.

Semi-closed: Unaffiliated voters as well as registered party members can vote.

Open: Voters can vote in any party’s primary.

Non-partisan: All candidates for a given office are listed on a single ballot regardless of party, and the top two go on to compete in the general election, regardless of party. These are often called “top-two” or “jungle” primaries.

In no state are voters legally allowed to participate in more than one party’s primary election in a given election cycle. If you vote in the Democratic primary, for example, then you’re not allowed to vote in the Republican one.

To complicate matters, presidential primaries are often handled differently with respect to whether primaries are open, semi-closed, or closed, and some states use caucuses and state-level conventions rather than primaries to select delegates for the national presidential nominating conventions. This year the state of Washington had both caucuses and a presidential primary, and the results of the presidential primary had no effect.

Caucuses are paid for and run by the parties according to their own rules. Primaries (presidential and otherwise) are paid for and regulated by the states.

Here’s how the numbers break down for state-level offices in 2016:

• 9 states and Washington DC have closed primaries
• 9 states have semi-closed primaries
• 7 states allow parties to choose to make the primaries closed or semi-closed
• 21 states have open primaries
• 3 states (Washington, California, and Louisiana) have non-partisan primaries
• 1 state (Nebraska) uses a mix of primary types for different offices

Presidential primaries and caucuses vary by party. On the Democratic side they are closed in 14 states, semi-closed in 12, and open in 24. For the Republicans, they are closed in 19 states, semi-closed in 9, and open in 22. Both parties’ primaries are closed in DC.

For a complete breakdown, see http://www.fairvote.org/primaries.

Incidentally, FairVote, like many other references, distinguishes two types of open primaries: “open” and “partly open.” In the former, states don’t register voters’ party affiliations and let voters pick a party when they vote. The other states do register voters by party but allow them to change party affiliation at any time, including when voting. Since in both cases voters can choose which primary to vote in at the last minute, I’m counting both types as “open.”

In fact, it’s worth noting that the only thing that distinguishes open primaries from closed and semi-closed ones is the deadline for picking a party. In New York’s closed-primary system, already registered voters who want to change their existing party affiliation must do so at least 25 days before the date of the previous year’s general election. No other state comes close to that, and only five states besides New York require voters to change their party affiliation more than two months before election day for the primary. In effect, open primaries simply reduce the advance notice requirement to zero.

A separate question is whether primaries ought to be open, semi-closed, or closed. I’ll get around to my thoughts on that, for whatever they’re worth, in another post.

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