Nearly 150,000 mail-in ballots were rejected in California's June primary election, a record high. The main reason was that ballots arrived after the deadline. Election officials say the large number of late-arriving ballots is unusual. Experts suggest that changes in how the U.S. Postal Service handles postmarks may have caused delays. Postmarks help prove when a ballot was mailed. If the postmark is missing or unclear, the ballot may be considered late. The new procedures could have slowed down mail delivery, leading to more ballots arriving after the cutoff. This issue affected many voters, raising concerns about access to voting. California has expanded mail-in voting in recent years, making ballots more common. But the high rejection rate has sparked calls for a review of postal policies. Officials are looking into ways to prevent similar problems in future elections. The rejected ballots represent a small fraction of the total votes cast, but the number is still significant. Voters are advised to mail their ballots early to ensure they are counted.