Vote by mail underway in California: How many get rejected?

FRESNO, Calif. (KFSN) -- Election Month is officially underway in California as county elections offices opened for early voting and drop boxes are now accepting ballots.

This year's election will lean heavily on mail-in ballots because of the coronavirus.

64 steel boxes are open for voters to drop off ballots across Fresno County as of Monday.

Election officials will collect votes from the 700-pound boxes at least every four days from now until October 24, when they start daily pickups.

It's a big operation, but elections clerk Brandi Orth says the county is prepared.

"The state of California has been doing vote by mail in large volumes for many many years," she said.

In fact, analysis by the ABC Owned Television Station's data journalism team's showed almost 162,000 people voted by mail in Fresno County in 2016 and more than 163,000 in 2018.

Orth tells us 172,000 people cast mail-in ballots in primaries this March. That's 86% of all votes.

President Trump has cast doubt about fraud with these ballots, and Fresno County's GOP chairman Fred Vanderhoof agrees this year is different because everyone in California is supposed to get a ballot in the mail.

"This is different where you're just sending mail-in ballots carte blanche to millions of people across the country and there's no chain of custody," said Vanderhoof. "There's no way of determining who gets them."

Orth says she's never seen a voter fraud case prosecuted in Fresno County in 26 years at the elections office.

The main preventative measure is the mandatory signature on the back of the purple ballot envelope, which they compare to the signature in your voter registration file.

"If, after multiple levels of computerized and human review, it is determined the comparison still isn't good, then the election official will mail you a letter saying you have an opportunity to cure your signature," Orth said.

In March, she says Fresno County sent out 2,544 letters because envelopes had "no signature" or a "mismatched signature" and offering voters the chance to fix it.

Only 527 ballots didn't get fixed and never got processed, so they rejected about 0.3% of ballots.

Our analysis showed the county rejected about 1% of vote-by-mail ballots in 2016, but you can make sure yours gets counted, especially if you cast it early.

Once you drop off your ballot, you can track it online. The state provides a service called "Where's My Ballot?" to follow it until it's counted.

ABC News data journalist Mark Nichols contributed to this report.