UW Elections Database Vote-by-Mail Research

Washington State administers a fully vote-by-mail election system. Ballot envelopes must be signed and deposited in an official drop box by 8:00 PM on election night, or mailed and postmarked by the date of the election. Ballot signatures are processed by county elections staff when ballots are received. Under circumstances where a signature is determined not to match state records, or where a ballot is missing a signature, the ballot is then “challenged” by county elections staff. Voters with a challenged ballot receive a written notice sent through first-class mail from the county elections office that their ballot signature could not be matched to the voter signature on file or was missing, and a declaration is included that allows the voter to present a valid signature to the county elections office to correct or “cure” the ballot. Challenged ballots that are not cured before county elections offices certify election results are rejected.

Starting in Spring 2022, the Secretary of State’s office and the Washington State Legislature have contracted with the Evans School of Public Policy & Governance at the University of Washington to complete additional research investigating trends in ballot rejections, potential causes of ballot rejections, and recommendations for improving the vote-by-mail experience in Washington state.

Core research questions of this work include:

• How do voters experience the vote-by-mail, ballot return, and ballot curing processes?
• To what extent are challenged ballots cured by voters?
• How do cure rates vary by voter demographics and geographic location?
• How have trends and patterns in ballot rejections varied over time? Do rates of ballot rejections vary by voter demographics or geographic location?
• What are common and best practices used by county elections offices to process ballots and support voters’ efforts to cure ballots?

The UWED Vote-by-Mail Research Report Series provides short research briefs and reports focused on key aspects of the vote-by-mail experience in Washington state. Research reports contain timely analyses of voter data that is publicly available from the Washington Secretary of State.

Patterns and Trends in Rejected Mailed Ballots in Washington State: 2020 – 2024

A September 2025 report analyzes voter-level ballot data from primary and general elections from 2020 to 2024, to better understand the vote-by-mail experience in Washington State, with particular attention to outcomes of ballot curing processes and rejection of ballots not cured. Several key research questions guide this report: To what extent are signature challenged ballots cured by voters? How do cure rates vary by voter demographics and geographic location?How have trends and patterns in ballot rejections varied over time? Do rates of ballot rejections vary by voter demographics or geographic location? How do the reasons for which ballots are rejected vary over time, voter demographics, and geographic location?

This September 2025 report found:

1. Across primary and general elections from 2020 to 2024, 1.6 percent of ballots cast were challenged for a missing signature or a signature that did not match the signature on file.
2. In primary and general elections since 2020, about 60 percent of ballots with signature challenges (missing signature or mismatched signature) have been cured before county elections officials submit election results to the State.
3. Overall, 1.4 percent of all primary ballots cast and 1.0 percent of general election ballots cast were rejected across elections from 2020 to 2024.
   • A very small percentage of all ballots cast were rejected for a signature that does not match the signature(s) on file – roughly about 0.5 percent of all ballots cast in any given primary or general election.
   • An even smaller percentage of cast ballots – just 0.2 percent – are rejected for missing a signature on the ballot envelope.
   • Roughly half of all ballots rejected in primary elections and in many general elections are rejected because they arrive late to county offices.
4. We estimate that voters of color have higher ballot rejection rates than White voters. For example, in general elections from 2020 to 2024, Black (1.3 percent), Hispanic (1.5 percent), and Asian (1.5 percent) voters experienced ballot rejection rates much higher than White voters (0.9 percent).
5. Self-identifying male voters have slightly higher ballot rejection rates than self-identifying female voters in both primary and general elections.
6. Younger voters have a much higher ballot rejection rate than older voters. Roughly 4 percent of ballots cast by voters 18 to 25 years old from 2020 to 2024 were rejected, compared to less than 1 percent of ballots cast by voters 66 or over during that time. Younger voters are much more likely to have ballots rejected due to signature mismatch than older voters.

Understanding Patterns and Trends in Rejected Mailed Ballots in Washington State

A November 2023 research report examined trends and patterns in mailed ballot rejections in primary and general elections from 2012 to 2022. In addition, this report features insights from interviews and in-person observations with county auditors and election staff, as well as surveys and in-depth interviews with voters in Washington State who had their ballots rejected in a recent election. The report found:

1. Overall, 1.5 percent of all primary ballots cast and 1.1 percent of general election ballots cast were rejected across elections from 2012 to 2022.
2. A very small percentage of all ballots cast were rejected for missing a signature or having a signature that does not match what is on file – usually about 0.5 to 0.6 percent of all ballots cast.
3. Roughly half of all ballots rejected in primary elections and in many general elections arrive late to county offices.
4. There is evidence that voters of color often have higher ballot rejection rates than White voters.
5. Self-identifying male voters have slightly higher ballot rejection rates than self-identifying female voters in both primary and general elections.
6. Younger voters have a much higher ballot rejection rate than older voters.
7. In primary and general elections since 2020, about 60 percent of ballots with signature challenges (missing signature or mismatched signature) have been cured before county elections officials submit election results to the State.

The report concludes with recommendations for research, policy, and practice to reduce the number of rejected ballots, increase ballot cure rates, and improve the voter experience in Washington State

Working Papers

• Allard, Scott W., Jacob Grumbach, Calista Jahn, Lauren Woyczynski, and Isaiah Wright. “Understanding Patterns and Trends in Rejected Mailed Ballots in Washington State.”
• Allard, Scott W., Jacob Grumbach, Lauren Woyczynski, and Isaiah Wright. “Ballot Curing in Primary and General Elections within Washington State.”
• Allard, Scott W., Isaiah Wright, Lauren Woyczynski, Jacob Grumbach, and Katie deCourcy. “Ballot Return Method and Receipt Timing in Washington State, 2020-24.”
• Allard, Scott W., Lauren Woyczynski, Isaiah Wright, Katie deCourcy, and Jacob Grumbach. “Vote-by-Mail within Tribal Reservations in Washington State.”

Presentations

• Southern Political Science Association (SPSA) Annual Meeting – January 2023
• Association for Public Policy Analysis and Management (APPAM) Annual Meeting – November 2024
• American Political Science Association (APSA) Annual Meeting – September 2025
• Election Sciences, Reform, and Administration (ESRA) Annual Meeting – June 2026
• American Political Science Association (APSA) Annual Meeting – September 2026

News Coverage

• “Washington voters of color more likely to have ballots challenged, per report” KUOW, September 2026
• “WA voters of color more likely to have ballots challenged, per report” Washington State Standard. September 2026
• “Counting the Voters: Half a million ballots were rejected between 2012 and 2022.Whose were they?” NWPB, June 2024
• “Nearly 99% of WA ballots are accepted, what’s going on with the 1% that aren’t?” KUOW, August 2024