There’s still time to return your ballot for the 2026 general election, but if you’re planning to vote by mail, you may want to hurry. That’s according to a research brief posted Oct. 21 by a team led by the University of Washington, which found that ongoing changes to U.S. Postal Service mail processes could double the percentage of ballots that arrive too late to be counted.
Researchers estimate the mail delays could cause tens of thousands of otherwise valid ballots to be rejected. These mail delays disproportionately impact rural voters and those in outlying suburban communities.
“This could affect 20,000 or more voters who put their ballots in the mail ahead of election day,” said research lead Scott W. Allard, professor of public policy and governance at the UW. “That may sound like a small number of voters in the grand scheme of things, but it could be really consequential, particularly in rural and outer suburban communities.”
The research brief — part of a broader study of mail-in ballots led by the UW Evans School of Public Policy and Governance — has not yet been peer-reviewed. Researchers plan to submit it to an academic journal in the coming months.
State law requires every ballot postmarked by Election Day to be counted. That system relied on the Postal Service’s practice of postmarking mail on the date it’s received. But new policies first rolled out in October 2023 shifted how the agency collects and processes mail.
Under the Regional Transportation Optimization (RTO) program — part of an agency-wide modernization effort announced in 2021 — mail in ZIP codes more than 50 miles from a regional center is collected only once a day. That mail may not be postmarked until it reaches a processing facility, which could be the next day or even later.
RTO was implemented in about two dozen Washington ZIP codes in February 2024 and has since been expanded to cover a large portion of the state. Rural voters are particularly likely to live in an RTO ZIP code, including over 90% of rural voters who voted in the 2024 general election.
To project the delays’ effects on ballot rejection rates, researchers analyzed voter-level ballot data and county-level rejection data from the Washington Secretary of State. They found that between 2020 and 2025, about 11% of primary ballots and nearly 5% of general ballots were postmarked before Election Day, but not received until after. While counted in past elections, these last-minute ballots are those most likely to be impacted this year.
Researchers also found that the late ballot rejection rate has risen significantly since RTO was implemented in 2024. Across Washington, the county average late ballot rejection rate was 1.1% in the 2025 general election — about twice as high as the typical rate in general elections. In that election, the ballot rejection rate for voters in RTO ZIP codes was 3.2%, more than double the rate for those in urban areas.
It’s difficult to project exactly how many voters are at risk of having their ballots rejected in 2026, but Allard said he expected the number to rise.
“I think we’re at risk of having 1% to maybe even 1.5% of all ballots rejected for being late due to postal service delays, which would be unprecedented statewide,” said Allard, who is the Daniel J. Evans Endowed Professor of Social Policy.
He encouraged voters to consider using official ballot dropboxes or putting their ballots in the mail at least a week before Election Day, which this year is Tuesday, November 3. Voters taking ballots to the post office also can ask their postal worker to postmark their ballot envelope on the spot.
“It shouldn’t fall only on the voters to solve this problem,” Allard said, “but there are steps we can all take to ensure our ballots are received on time.”
Co-authors include Lauren Woyczynski, UW doctoral student of sociology; Isaiah Wright, UW doctoral student of public policy and governance; and Jacob Grumbach of the University of California, Berkeley.
For more information or to reach the researchers, contact Alden Woods at acwoods@uw.edu.