Universal vote-by-mail doesn't benefit any political party, study finds

Election workers sort vote-by-mail ballots for the presidential primary at King County Elections in Renton, Washington on March 10, 2020. (Photo by Jason Redmond / AFP) (Photo by JASON REDMOND/AFP via Getty Images) less Election workers sort vote-by-mail ballots for the presidential primary at King County Elections in Renton, Washington on March 10, 2020. (Photo by Jason Redmond / AFP) (Photo by JASON REDMOND/AFP via Getty ... more Photo: Jason Redmond / AFP Via Getty Images Photo: Jason Redmond / AFP Via Getty Images Image 1 of / 35 Caption Close Universal vote-by-mail doesn't benefit any political party, study finds 1 / 35 Back to Gallery

Republican officials in recent weeks have sought to portray universal vote-by-mail as a partisan issue.

President Donald Trump said in March that the policy would mean "you'd never have a Republican elected in this country again." Georgia's Republican Speaker of the House said VBM would be "extremely devastating to Republicans and conservatives in Georgia." Partisanship concerns also motivated Wisconsin Republicans' refusal to expand absentee voting in the state's primary election last week.

But these notions are patently incorrect, according to a new study that reaffirms and expands upon years of prior research: no party benefits when a state switches to universal vote-by-mail.

The question has taken on new relevance in the context of the coronavirus pandemic, when in-person voting raises health risks to both voters and poll workers.

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Universal VBM typically works like this: Ballots are automatically sent to every registered voter, who in turn are supposed to fill them out and mail them back to election officials. In some states, like Colorado, voters have the additional option of either dropping ballots off at specified locations on Election Day, or voting in person at those same locations.

According to the National Conference of State Legislatures, Colorado, Hawaii, Oregon, Washington and Utah currently have universal VBM. A sixth state, California, allows its counties to implement vote-by-mail at their discretion.

In a number of these states, vote-by-mail was rolled out at the county level on a staggered basis. This setup allowed a team of political scientists at Stanford University to conduct a natural experiment: "by comparing counties that adopt a vote-by-mail program to counties within the same state that do not adopt the program, we are able to compare the election outcomes and turnout behavior of voters who have different vote-by-mail accessibility but who have the same set of candidates on the ballot for statewide races," they write.

To test partisan effects, they compiled a data set containing county-level election results, as well as public voter file data containing the party registration of voters in California and Utah. The data covered elections from 1996 to 2018.

After controlling for county-level differences, the data showed "a truly negligible effect" on partisan turnout rates. The effect on partisan vote share was similarly indistinguishable from zero.

One thing they did find was a modest boost in across-the-board turnout. "Vote-by-mail causes around a 2-percentage-point increase (estimates range from 1.9 to 2.4 percentage points) in the share of the voting-age population that turns out to vote."

None of these findings would come as a surprise to other political scientists who have studied the issue. Prior studies have yielded similar findings.

The Stanford study, however, "should increase our confidence in these views," the authors write, "both because our data permits a stronger research design than was previously possible and because our data set runs through the 2018 midterm elections, allowing for the most up-to-date analysis available."

The data do come with one big caveat: The study can't predict what (if any) effect universal VBM might have in the midst of a pandemic, simply because that situation throws so many additional variables into the mix that it's impossible to control for. Would older people fearing for their health be more likely to participate with VBM, thus creating a partisan advantage for Republicans? Would otherwise disaffected younger voters be more likely to vote, creating an advantage for Democrats? It's impossible to say.

Nonetheless, the findings do underscore that partisan opposition to VBM over electoral concerns is a standpoint with no basis in empirical reality.