Nearly 150,000 California voters had their mail-in ballots rejected for the state’s June primary, a spike from recent elections even as the state attempts to make voting easier with the goal of boosting participation and counting every ballot.
California has become notorious for its ponderously slow vote counts that can drag on for weeks and sometimes longer, largely the result of multiple changes over the years that were intended to increase turnout but have done little to achieve that. Among the changes: Every voter receives a mail-in ballot that can arrive at an election office seven days late and still be counted, provided the envelope is postmarked by Election Day.
Yet even with that generous weeklong window, the primary driver of the higher rejection numbers is late-arriving ballots, according to data compiled by the secretary of state’s office. Voting experts suspect the main problem is postmarks on ballots that came after Election Day, making them ineligible to be counted. The culprit could be U.S. Postal Service changes that might affect the timing of when postmarks are applied.
Late-arriving ballots drove the rejections
According to state data, 148,241 mail ballots were rejected in the June election, or a rate of 1.73% of all mail ballots.
In raw numbers, that’s up from the 2024 primary, when 108,982 mail ballots were rejected, or a 1.56% rate. In 2022, 105,818 mail ballots were voided during the primary, or a rate similar to 2024.
Lateness accounted for 93,479 rejected ballots in June, by far the largest category for disqualifying a ballot. That was up from about 70,000 in the 2022 primary and about 76,000 in the 2024 primary, though turnout in those elections was smaller compared to last June.
Kim Alexander, president of the nonpartisan California Voter Foundation, said the jump in rejected ballots because of lateness is a major concern that — along with postal procedures — might also be connected to a late surge in ballots in June. Many voters waited until the final days to make a decision in a wide-open and chaotic race for governor.
“Ballots rejected due to lateness are caused primarily to being postmarked too late to count, not because they arrived too late to count,” Alexander wrote in an email.
Rejection rates have fluctuated over time, but the growing number of those set aside for lateness compared to recent elections “does really demand the question why this is happening,” said Mindy Romero, director of the Center for Inclusive Democracy, a nonpartisan research group.
Lawmakers concerned about USPS postmark changes
In January, a group of mostly Democratic U.S. senators sent a letter to the U.S. Postal Service, alarmed that mail-processing changes might affect postmark dates for mail-in ballots during an election year that will determine control of Congress.
Updated agency policy says postmarks might not indicate the first day the Postal Service received the mail, but rather the day it was handled in one of its processing centers. Those centers are increasingly likely to be further away from certain communities because of recent consolidations within the Postal Service, which could further delay postmarks.
On Thursday, two Wisconsin Democrats, U.S. Sen. Tammy Baldwin and Gov. Tony Evers, called on the Postal Service to address delays that caused hundreds of ballots to arrive after Election Day in the state in April. In June, a federal judge halted President Donald Trump’s executive order that sought to create a federal voter list and limit who can receive a mail ballot.
Earlier this year, California election officials urged voters to send their mail ballots early, warning that Postal Service changes could lead to slower mail service.
In California, the highest mail ballot rejection rate in June — 3.52% — was in Tulare County, in the agriculture-heavy Central Valley. It was followed by Alpine County, south of Lake Tahoe, and Merced County, also in the Central Valley, which both notched a 3.36% rejection rate.
Mismatched signatures and multiple ballots in an envelope
Nearly 44,000 ballots were set aside because the voter’s signature didn’t match the one on record with county officials. Over 8,300 ballots were rejected because there was no signature on the returned ballot envelope.
In 743 cases, the voter had already cast a ballot, so the mail ballot was voided. Other reasons for rejection included a ballot being missing from the return envelope, or multiple ballots were sent back in a single envelope.
The data didn’t break down the uncounted ballots by party registration.
Florida, Texas and other large population states quickly wrap up vote counting, while California is a national laggard.
After the June primary, President Donald Trump seized on California’s reputation as the national slowpoke in vote counting to renew his long-standing criticism of the state’s elections, while the Republican’s Department of Justice launched an investigation into Los Angeles County’s elections.
There is no indication of any widespread problems with mail voting, which has gained in popularity among Democrats and Republicans alike. A report by the Brookings Institution published in 2025 found that the number of cases of mail voting fraud was minuscule — about four cases per 10 million mail ballots.