In advance of the WI primaries, most people expected turnout to be significantly lower than normal. In what is perhaps an example of anchoring bias, many journalists continue to write stories referencing the supposedly “low turnout,” as in a NYT story today. Charles Stewart and I have published an extensive analysis, in today’s Washington Post Monkey Cage, of turnout this year — which was 1.55 million — compared to prior WI presidential primaries. That analysis is much more detailed than my previous posts on this issue.

Excerpting a statistical piece is difficult, but here are a couple bits:

First, we used statistical estimation to compare 19 Wisconsin primaries, held from 1948 to 2020. With so many, the model had to be simple. We considered the comparative competitiveness of the two parties’ presidential primaries — and whether the incumbent president was running again or at the end of his two terms. We also took into account how Wisconsin primaries’ turnout dropped dramatically beginning in 1984, when the rise of “Super Tuesday” made Wisconsin’s primary votes less influential.

Using this approach, we found that in a “normal” 2020 election, roughly 26 percent of the voting-age population would have cast ballots, for about 1.2 million voters. That is far fewer than the 1.55 million votes actually cast. …

The 2012 Wisconsin primary most directly resembles this year’s in key ways. With President Barack Obama up for reelection in 2012, the Democratic primary was uncontested, like the Republicans’ this year. In 2012, 1,088,000 Wisconsinites voted: 788,000 in the Republican primary and 300,000 in the Democratic. In other words, 26 percent of the voting-age population cast ballots. [Turnout this year was 34 percent]

But that doesn’t quite capture the difference. We would expect a lower 2020 turnout than in 2012, because this year’s Democratic primary was fairly settled, while 2012’s Republican contest was still hotly contested: Mitt Romney won 44 percent of the vote, followed by Rick Santorum’s 37 percent and Ron Paul’s 11 percent.

As to why turnout was so surprisingly high, we speculate that:

The most likely answer is that Democrats are so mobilized in the Trump era — either for Democrats or against Trump — that they are showing up in unexpectedly high numbers, even under Wisconsin’s difficult pandemic circumstances. The 2018 midterm election in Wisconsin had the highest turnout that state has seen since World War II. And the 2019 supreme court spring election had the second-highest turnout among comparable elections over the past two decades, behind only 2011, when ideological control of the court was at stake.

In addition, allegations that the Republican legislature was trying to hold down turnout by not postponing the election might have further motivated Democrats to vote.

Do read the full piece for all the relevant qualifications.