SAN FRANCISCO >> The nation is again waiting on California to finish tallying votes almost a week after Election Day.

The state has most of the remaining undecided races that will determine the balance of power in the House, and its slow vote-counting process has drawn greater scrutiny — and some scorn — as each day goes by.

While many states tallied the bulk of their ballots within hours of polls’ closing, California still had nearly 5 million to count going into the holiday weekend, just under one-third of all of the ballots that were cast there.

Leaders in California defend the deliberate process as necessary to ensure that the tallies are accurate and that as many voters participate as possible. They say their generous provisions for voters give the public greater confidence.

The delay in full results has left Americans wondering why the balance of power in the House is yet to be known. It has also opened avenues for disinformation, with Democrats and Republicans seizing upon the incomplete results as evidence of voter fraud or manipulation.

Counting votes in California is not as simple as running ballots through a machine.

The state is one of a handful nationwide where every registered, active voter is mailed a ballot. Mail-in ballots take longer to process than those cast in person.

Election offices must verify that the signature on each envelope matches the voter’s signature on file. Instead of throwing out ballots that were filled out improperly, election workers in California spend days calling voters and giving them another chance to verify their signatures so that their votes can be counted.

This process, known as ballot curing, occurs in half of U.S. states. But because nearly all of California’s ballots are mailed or hand-delivered in envelopes, the verification process is more tedious than elsewhere.

And unlike most other states, California counts ballots that arrive up to a week late, as long as they were postmarked by Election Day.

Twenty years ago, only one-third of California voters cast ballots by mail, and 81% of votes were counted within two days of Election Day. In the primary election in March this year, when nearly 90% were cast by mail, only 59% had been counted within two days, according to an analysis by the nonprofit California Voter Foundation.

California gives counties 30 days to finalize their tallies, far longer than most states do. That means that counties can count at whatever speed suits them, hiring varying levels of reinforcements and drawing up different work schedules, as long as they finish by the deadline, said Secretary of State Shirley N. Weber, the top election official in California.

Weber said in an interview that she thought Californians were accustomed to a slower vote count and that other Americans became impatient only when there were national stakes, as is the case now with the House.

“That’s not our problem,” she said. “We go as fast as we can.”

California is responsible for the largest share of the outstanding ballots left.

Because Vice President Kamala Harris currently has 10 million fewer votes nationwide than President Joe Biden did in 2020, a handful of Democrats have made unfounded claims that Republicans must have caused millions of ballots for Harris to disappear. Some Republicans in turn have incorrectly asserted that the current count for Harris is a more accurate reflection of national support for Democrats and shows that Biden received fraudulent votes four years ago.

“Even actions that are actually just good-faith efforts to have a reliable election” can become fodder for conspiracy theories, said Eric Schickler, a political science professor at the University of California, Berkeley. “There’s a lot of suspicion and distrust of governmental institutions — this ends up playing into that.”

Weber said that she was aware that an information vacuum could lead to false narratives, but she did not think that providing results faster in California would do much to stop election conspiracists.

“They’re going to do that anyway,” she said. “The reality is that even things that have been resolved, they create stories about them. We want to count every vote.”

In 2022, it took two weeks to determine the winner of a tight U.S. House race in a Northern California district. In 2018, a long delay led then-Speaker Paul Ryan to question the integrity of the state’s voting system after Republicans lost several House contests in which it initially appeared that they would sail to victory.

As of Monday, nine of the 16 uncalled House races that will determine control of the chamber are in California, including in Orange County and the Central Valley. Five are among the most hotly contested in the nation.

Alameda County has counted more slowly than any other large county in California and had tallied only about one-third of its ballots two days after the election. The county does not have any battleground House races, but The Associated Press determined Monday that the Oakland mayor and Alameda County district attorney had both been recalled by voters.

Election offices do not process ballots 24 hours a day. Many count during normal business hours and give workers days off before the counts are complete. In Orange and Marin counties, employees were working Saturday and Monday but not Sunday. In Contra Costa County, counters stopped working Friday and will start again Tuesday morning.