There are states with similar primary structures, and there are states with later primaries. But no state has Washington’s combination of primary structure, large voter numbers and late calendar date. Put them all together, and you get a high-turnout election with a broad, relatively diverse electorate just a few months before the rest of the country votes for president.
What does Washington’s primary tell us this year?
If you used only Washington’s primaries to forecast voting trends in the U.S. House, you’d do relatively well: The primary’s subtle shifts left or right have tracked with the country’s in all but two election cycles since 2000.
But Washington state and the country don’t just move in the same direction. They also tend to move one way or another by similar degrees. If after every Washington primary election between 2000 and 2022 you predicted that the country as a whole would shift left or right by the same level as the state’s primaries, you would have been off by less than three percentage points, on average. Pretty good!
Last month, Washington’s House Democrats received 58 percent of the major party vote share across the state’s 10 House districts — three points better for Democrats than their result in 2022.
If that shift translated perfectly to the national vote, that would mean a move three points to the left of the 2022 House vote (when Republicans narrowly captured the House), lifting Democrats to 51 percent of the popular vote from 48 percent. That total would be about where Democrats finished in 2020 and two points better than Democrats’ result in 2016.
An analysis by SplitTicket, an independent election analysis site, went further, examining election results only in the nonurban parts of Washington state. They found that if you remove Seattle, Washington looks demographically similar to the key swing states of Wisconsin, Michigan and Pennsylvania. Since 2012, the primaries in those nonurban districts have consistently tracked the national House vote in November, though they are typically three to five points further to the right.
As with the rest of the state, the districts outside of Seattle have shifted modestly to the left since 2022, and are slightly to the left of where they were in 2020, perhaps another piece of good news for Democrats.
Can it tell us anything about the presidency?
Only to a point. The Washington primaries are helpful in thinking about the general mood of the country as it translates to the national popular vote, but it’s less useful as a predictor of presidential elections, where specific candidates, issues or economic conditions make a bigger difference. And, more important, there’s the Electoral College. As we know from the 2000 and 2016 presidential elections, the popular vote in a close race is only a partial indicator for how the most important battleground states will go.
As it happens, the 2016 primary results in nonurban Washington suggested Hillary Clinton might underperform in the Northern battlegrounds. She did.
Why Washington might be less predictive in 2024
There are other reasons to be cautious about the predictive power of Washington’s primary this year.
- We don’t know to what extent the August primary results were influenced by a highly turbulent July. President Biden announced his decision to exit the race on July 21, and the immediate Democratic excitement over Kamala Harris’s ascent to the nomination may have increased turnout in Washington’s primary, reflecting an early enthusiasm that may not be matched by Election Day.
- A lot has already happened since that primary, and still might. Since Washington’s primary, the nation has seen the Democratic National Convention, the first debate between Ms. Harris and Mr. Trump, a Taylor Swift endorsement and a second assassination attempt against Mr. Trump.
- There’s also no guarantee that Washington’s primaries will continue to move in parallel with the country at large. In an earlier era, between 1978 and 1998, Washington and the country as a whole trended in opposite directions more than they trended together.
If recent trends hold, however, the Washington primary suggests the country will shift three points to the left from 2022 — plus or minus three points. That’s roughly in line with today’s polling averages, whereas in 2020 the primary results correctly suggested that Mr. Biden’s big polling lead was overstated. Still, that’s a big margin of error for the most hotly contested House races, and a presidential race that is essentially a tossup.