Dickinson Researchers Find Partisanship Had No Effect on Mail-In Ballot Rejection Rates in Pennsylvania

Portrait of Adam Mast and Sarah Niebler standing in front of green shrubbery.

Adam Mast '25 and Associate Professor of Political Science Sarah Niebler. Photo by Dan Loh.

Research from Dickinson's Department of Political Science indicates local election workers are conducting their work responsibly and without bias 

by Craig Layne 

A new report on mail-in voting in partnership with nonpartisan organization Keep Our Republic and conducted by Associate Professor of Political Science Sarah Niebler and Adam Mast ’25 finds partisanship did not affect whether an individual’s mail-in ballot was rejected due to voter error, with nearly identical percentages of ballots rejected across both major political parties.  

Statewide, 1.94% of Democratic ballots and 2.01% of Republican ballots were rejected during the 2023 Primary Election in Pennsylvania. While rejection rates differed slightly across counties, they were overall low and did not vary based on partisanship, age, education, income, or race of county residents.   

“It is not surprising, but good to see, that the party affiliation of the voter does not have an impact on whether their ballot was rejected,” says Niebler, who led the study. “People do sometimes make mistakes when filling out and submitting mail-in ballots, but this study shows those mistakes are rare and not more likely to happen to one party’s voters over the other. Hopefully, the Commonwealth will continue its educational efforts, and mistakes will be even less frequent in future elections.”  

“This important insight will bolster faith in the mail-in ballot process as being fair and nonpartisan,” says Keep Our Republic Pennsylvania Advisory Council member and Dickinson President John E. Jones III ’77, P’11. “Professor Niebler and Adam Mast are both furthering their field and strengthening the fabric of democracy. We are tremendously proud of them.” 

The report also revealed a series of other notable findings. Democrats were much more likely to request mail-in ballots than were Republicans (71.18% of all requests were by Democrats and 22.11% by Republicans) and were slightly more likely to return their mail-in ballots compared to their Republican counterparts (19.74% of Democrats who were approved for a mail-in ballot did not return them, while 23.23% of Republicans did not so).  

Older voters tended to request and return their ballots at higher rates when compared to younger voters. Senior citizens’ mail-in ballots were rejected due to voter error at a lower rate than were non-seniors. Additional demographic variables such as education, race, poverty status and homeownership rates did not have an influence over ballot return or ballot rejection rates when looking at county-level data.  

“Working with Keep Our Republic and Professor Niebler has been a great way for me to get some hands-on experience with research in the political world,” says Mast, the student researcher. “I learned a lot from it, and I am happy to be a part of important work.” 

“This analysis by the Dickinson College team is an important contribution to our understanding of how mail-in ballot processing is being handled by county election officials,” says Ari Mittleman, executive director of Keep Our Republic, a nonpartisan civic education nonprofit dedicated to preserving a republic of laws and strengthening the checks and balances of our democratic operating system. “It indicates that local election officials are acting properly and not allowing partisanship to affect their decision making. We are looking forward to analysis of future elections by Dickinson’s experts.” 

The state mail-in voting law, which passed with bipartisan support in 2019, has been widely utilized by Pennsylvania, with about 39% of voters choosing mail voting in the COVID-affected 2020 general election and nearly 23% of 2022 general election votes cast by mail. Nevertheless, mail balloting has become a main focal point in a partisan campaign to sow distrust in Pennsylvania elections.  

Previously, Dickinson hosted a conversation on defending democracy with Keep Our Republic leaders that also served as the launch of the organization’s Pennsylvania Advisory Council, chaired by former Pennsylvania Gov. Tom Corbett. 


Published October 19, 2023