As the coronavirus persists and the U.S. November election nears, some states are expanding options for voters to cast their ballot either by mail or absentee – a decision that has raised concerns that mail-in voting could favor one political party over the other.

According to Stanford research, mail-in voting does not appear to benefit one political party over the other. However, challenges to mail-in and absentee voting remain as states and voters make a shift this November. (Image credit: Getty Images)

But contrary to what some skeptics believe about partisan effects, multiple studies by Stanford scholars have found that mail or absentee voting does not appear to benefit either political party.

While absentee and mail-in voting has never been attempted at a scale as large as what is anticipated this fall, some states have already implemented these types of voting programs in their own elections. By studying the results from these elections, Stanford scholars have been able to examine effects on turnout, anticipate how mail-in voting might unfold nationally in November and identify challenges that lie ahead, such as ensuring that every ballot gets counted.

Here are some of their findings.

No party advantaged over the other

One recent study led by Andrew Hall looked at data from California, Utah and Washington – three states that have gradually expanded their state’s vote by mail programs. These staggered rollouts allowed Hall and his research team to compare election outcomes and voter behavior.

Hall, a professor of political science in the School of Humanities and Sciences and a senior fellow at the Stanford Institute for Economic Policy Research (SIEPR), found that these policies did not appear to affect voter turnout for either Republicans or Democrats. Neither did mail-in voting impact the share of votes that went to Democratic candidates, according to Hall’s analysis.

While the researchers found that mail-in voting had no meaningful partisan effect, they did find that overall turnout increased by about 2 percentage points, on average. The research was first released as a working paper by SIEPR and then published in PNAS.

“Our paper has a clear takeaway: claims that vote-by-mail fundamentally advantages one party over the other appear overblown. In normal times, based on our data at least, vote-by-mail modestly increases participation while not advantaging either,” Hall and his co-authors wrote in the paper.

Hall is continuing to explore absentee voting, including an in-depth analysis of a primary election held during the coronavirus pandemic. Overall, his findings are consistent with his earlier study.

Given the unprecedented challenges of holding an election during this pandemic, it is hard to predict exactly what will unfold in November, said Hall in an interview with Stanford News Service.

“Vote-by-mail is an extremely helpful part of the overall, non-partisan election toolkit, but it is not a panacea,” Hall said. “Voters should consider their local context, including prospects for logistical issues with vote-by-mail and the safety precautions their local officials are implementing to support in-person voting before deciding how they want to vote.”

Boosting voter turnout

Stanford political scientists Adam Bonica and Hakeem Jefferson recently analyzed election results in Colorado, one of the few states that conducts its elections exclusively by mail. In 2013, the state implemented a new policy that required ballots to be mailed to every registered voter prior to the election.

Bonica and Jefferson examined the impact this shift had on voter turnout in a working paper co-authored with Jacob M. Grumbach at the University of Washington and Charlotte Hill of UC Berkeley.

In their analysis of data from five elections held between 2010 and 2018, the researchers found that voter turnout increased by about 9.4 percent following the 2013 policy implementation. They found a large boost particularly among young people: turnout increased by 15 percentage points in voters 30 years old and younger.

Mail-in voting also had positive effects among blue-collar workers, voters without a high school diploma, voters with less wealth and voters of color, Bonica and Jefferson reported in the paper.

“These findings suggest that making it easier to vote increases electoral participation among those who may otherwise remain unengaged,” they wrote.

Moreover, the scholars found little evidence that Colorado’s all-mail voting disproportionately benefited Republican or Democratic Parties. However, Independents, who had historically engaged in politics less frequently than their Republican and Democratic peers, turned out at nearly 12 percentage points higher than in previous elections.

Overall, Bonica and Jefferson concluded that mail-in voting helps make democratic participation more inclusive. “Colorado’s experience demonstrates that all-mail voting is not only safer than in-person voting but also better for democratic representation, with all age, income, race, occupational and education groups benefiting from its introduction,” wrote the scholars.

The scholars also recognize challenges in making a rapid switch for the November 2020 election and meeting the increased demand of mail voters. As learned from Colorado, they suggest that in-person voting options should be maintained with necessary safety measures so that people who miss the deadline to receive a mail-in or absentee ballot can still vote.

Mail-in voting in a Covid-19 world

As state and county election officials prepare for November, problems remain about how to administer the election, including issues about how to ensure that all mail-in ballots are counted, which is a top concern for Nathaniel Persily, the James B. McClatchy Professor Law at Stanford and former Senior Research Director of the Presidential Commission on Election Administration.

“In such a short period of time it is very difficult for states to adapt to this new environment and it requires changes at every step in the administration of the election, from the beginning of registering votes to the end of counting their votes,” Persily said in an interview with Stanford News Service.

Persily pointed to research conducted by the Healthy Elections Project, a bi-partisan effort he is co-leading with Charles Stewart III of Massachusetts Institute of Technology to address the problems that the COVID-19 pandemic poses to the 2020 election. Researchers, who include Stanford students, found that in Florida’s 2020 primary election, mail-in ballots cast by African Americans, Latinos, first-time voters and young voters were significantly less likely to have their vote counted – either because it was received late or signatures were missing or did not match the signature on file.

“That’s a real concern as we approach the election,” Persily added.

Moreover, shifting to mail-in ballots presents an additional set of logistical challenges, particularly among states that have a long history of in-person voting. For example, states will need to acquire infrastructure – such as mail-in ballots, sorters and scanners – needed to meet the increased demand, Persily said in a recent interview with Stanford Legal. The Healthy Elections Project has also prepared a vote-by-mail resource guide to educate voters and local election officials on the process, including guidance on signature verification and vote tallying.

Persily says that tens of millions of Americans must prepare themselves for voting in a different way than they are used to.

“We need to start treating this election like we would a natural disaster, like a hurricane or earthquake. We need to mobilize around all levels of government and civil society and that includes Congress appropriating more money and it includes massive efforts about educating people about how to vote safely and we need people to volunteer,” Persily said.