That voter turnout percentage reported the day after Election Day may be the most misinterpreted statistic in California politics.

On Wednesday, it stood at 21 percent, based on official numbers that showed 4.1 million ballots were cast Tuesday out of more than 19 million registered voters.

But the percentage of registered voters who participated will grow steadily and significantly as county election officials sort through and count millions of late-arriving ballots.

Click to resize

The task could take weeks, leaving the outcomes of dozens of races in limbo and frustrating candidates and supporters who want to move on.

For the past several elections, more than half of Californians have voted by mail instead of going to polling places on Election Day. That causes delays because ballots typically are mailed or brought into polling places late, stacking up in election offices while officials conduct Election Day voting. In the ensuing days, each mail-in ballot that arrived in the final hours must be opened and the registration and voter signature checked against the official voter roll.

"Voting by mail has gone up a lot," said Sam Mahood, spokesman for Secretary of State Alex Padilla. "And a lot of people wait until the last day to drop off their ballots."

This is the second election voters have had even more time to get their ballots in because of a new law passed by the Legislature and signed by Gov. Jerry Brown. Before 2016, a ballot had to arrive at the county elections office by Election Day in order to be counted. Now, it must only be postmarked by Election Day and can arrive up to 72 hours later.

And Tuesday, a printing glitch in Los Angeles County left an estimated 118,000 voters off of voter rolls, causing thousands to file provisional ballots. "Those take time to count because the officials have to verify registration and make sure they haven't voted anywhere else," Mahood said.

So just how many ballots are out there, waiting to be processed? It's too early to say. Counties will count the number of unprocessed ballots over the next day or so and report to the state.

In November 2016, a huge-interest presidential election, the counties had to deal with more than 4 million unprocessed ballots long after the concession and acceptance speeches had been delivered on Election Day. The initial 51 percent turnout eventually landed at more than 75 percent.