Two weeks after the election, as many as 41,700 mail-in and provisional ballots remain uncounted in Sonoma County, about 23 percent of the total cast by voters.

The tally of unprocessed ballots has left at least three local races undecided. And that is unlikely to change for another two weeks, with county officials saying it's probable they will need the full 28 days allowed under state law, until Dec. 4, to complete the count and certify the vote.

The long wait isn't unusual. Most counties still are poring over mail-in and provisional ballots in an effort to meet the deadline.

Until then, Sonoma County will not provide updates on the vote count, spurning a practice that officials from other counties say is useful to keep voters and candidates informed.

Janice Atkinson, Sonoma County's elected clerk-recorder-assessor and registrar of voters, disagrees. She said preliminary updates don't work well with the county's vote-processing system and would only delay the final count. She also questioned the value of releasing periodic, unofficial results.

"I want the candidates to have final results as soon as possible," she said. "When you have a close contest, you have to count all the ballots. Updates don't help."

The decision of whether to update vote counts before releasing final results is left up to counties. In the North Bay, Marin County updates its numbers while Mendocino and Napa counties do not.

Some see value in the updates, saying they provide transparency, said Cathy Darling Allen, president of the California Association of Clerks and Election Officials. Others see them as a distraction.

"It's a personal decision for each registrar to make," Darling Allen said.

Shasta County, where Darling Allen oversees elections, provides updates.

The interim updates do not delay the final vote count in Marin County, said Elaine Ginnold, Marin's registrar of voters.

"I think it is good information for people. Even if it isn't finished, people want to know what is happening," Ginnold said.

The issue resurfaces especially in general elections amid the clash of two trends: The expectation of immediate voting results through the help of digital technology and the growth of mail-in ballot use, which actually can delay final results, requiring extensive work to verify and count votes.

Provisional ballots cast by voters whose registration or polling place is in question can take even more time to tally, Darling Allen said.

As of Monday, only 13 of California's 58 counties had completed their final count, according to a report by the state Secretary of State's Office.

Aside from Alameda County, most were large rural counties with sparse populations.

Among the counties still working away, Los Angeles has the most uncounted ballots at 518,000. Behind it are Orange County (107,000), San Diego (92,000) and Sacramento (77,292).

Based on revised numbers county officials provided, Sonoma County ranks 10th on the list, with 35,553 uncounted mail-in ballots and an estimated 6,150 provisional ballots.

Atkinson was unable to specify Monday exactly which districts those uncounted ballots came from. But she used turnout rates from the total number of mail-in ballots returned to estimate that just more than 15,000 may come from the 10th Assembly District, where incumbent Democrat Michael Allen is trailing Democratic challenger Marc Levine.

Levine, a San Rafael city councilman, has claimed victory in the race and widened his lead over the weekend to two percentage points, based on Marin County vote updates. Allen has refused to concede, saying the race could hinge on the final results.

Other close races where uncounted ballots could affect the outcome include:

The Sebastopol City Council race, where incumbent Kathleen Shaffer trailed challenger John Eder by nine votes in a battle for the final contested seat. Atkinson estimated just more than 700 mail-in ballots could affect the race.

The Santa Rosa school board race, where newcomers Jenni Klose and Brian Noble were separated by 1,055 votes, with Klose leading. Atkinson estimated more than 14,200 mail-in ballots could factor in that race.

You can reach Staff Writer Brett Wilkison at 521-5295 or brett. wilkison@pressdemocrat.com.