California's recent June primary saw nearly 150,000 mail-in ballots rejected, marking a significant surge from previous elections, despite the state's ongoing efforts to simplify voting and boost participation.
This substantial increase underscores persistent challenges within the state's electoral process, which has long been criticized for its ponderously slow vote counts that can drag on for weeks.
The state has implemented various measures aimed at making voting more accessible, including the automatic mailing of ballots to every registered voter.
These mail-in ballots are designed to be counted even if they arrive up to seven days after Election Day, provided they bear a postmark from the election date.
Yet, according to data from the secretary of state's office, the primary driver behind the heightened rejection numbers is late arrival. Voting experts suspect the core issue lies with postmarks applied after Election Day, rendering these ballots ineligible for tabulation.
Changes within the U.S. Postal Service (USPS) are increasingly believed to be a contributing factor to the timing of when these crucial postmarks are applied.
In the June election, 148,241 mail ballots were ultimately rejected, representing 1.73% of all mail ballots cast.
This figure marks an increase from the 108,982 mail ballots rejected in the 2024 primary, which had a 1.56% rejection rate.
In 2022, 105,818 mail ballots were voided during the primary, with a rate similar to that of the 2024 primary. Lateness alone accounted for a staggering 93,479 rejected ballots in June, making it by far the largest category for disqualification.
This number is up from approximately 70,000 in the 2022 primary and 76,000 in the 2024 primary, though turnout in those earlier elections was comparatively smaller.
Kim Alexander, president of the nonpartisan California Voter Foundation, expressed significant concern over the jump in late rejections.
She suggested this, alongside evolving postal procedures, might be linked to a late surge in ballots as many voters delayed their decisions in a competitive gubernatorial race.
Alexander stated, "Ballots rejected due to lateness are caused primarily to being postmarked too late to count, not because they arrived too late to count."
Mindy Romero, director of the Center for Inclusive Democracy, added that the growing number of late rejections "does really demand the question why this is happening," prompting a closer examination of the underlying causes.
Lawmakers have also voiced concerns regarding USPS changes. In January, a group of predominantly Democratic U.S. senators wrote to the Postal Service, alarmed that mail-processing alterations could impact postmark dates during a crucial election year that will determine control of Congress.
An updated agency policy indicates that postmarks might reflect the day mail is handled at a processing center, rather than the day it was initially received.
With recent consolidations, these centers are often further from certain communities, potentially exacerbating delays. In a related development, two Wisconsin Democrats, U.S. Sen. Tammy Baldwin and Gov. Tony Evers, called on the Postal Service in April to address delays that caused hundreds of ballots to arrive after Election Day in their state.
Earlier this year, California election officials had already urged voters to mail ballots early, citing potential USPS service slowdowns.
Beyond lateness, nearly 44,000 ballots were rejected due to mismatched signatures, while over 8,300 lacked any signature on the returned envelope.
Other reasons included voters having already cast a ballot (743 cases), a ballot being missing from the return envelope, or multiple ballots sent back in a single envelope.
The data did not provide a breakdown of these uncounted ballots by party registration. Geographically, Tulare County, located in the agriculture-heavy Central Valley, recorded the highest mail ballot rejection rate in June at 3.52%.
It was followed by Alpine County, south of Lake Tahoe, and Merced County, also in the Central Valley, both at 3.36%.
California's reputation for slow vote tabulation contrasts sharply with states like Florida and Texas, which quickly finalize their counts. Donald Trump has previously leveraged California’s protracted counting to criticize the state’s elections, and his Department of Justice launched an investigation into Los Angeles County’s elections.
In June, a federal judge halted an executive order by Donald Trump that aimed to create a federal voter list and restrict mail ballot eligibility. Despite these controversies, mail voting has gained bipartisan popularity, and a 2025 report by the Brookings Institution found mail voting fraud to be minuscule, with approximately four cases per 10 million mail ballots, suggesting that the integrity of the system remains largely intact despite the operational challenges.
