Voter turnout in San Mateo County in the 2016 presidential election, at 81.57 percent of registered voters, was well above turnouts for recent off-year elections, but it also exceeded the 78.83 percent turnout for the 2012 presidential election.

The 396,341 people who were registered to vote in the county this time around was an all-time high, according to Mark Church, the county's chief elections officer.

"This was truly a historic presidential election for San Mateo County voters," he said in announcing the certified results Dec. 5.

Turnout was higher still, at 87 percent, in the election for the Menlo Park Elementary School District governing board, according to Elections Office records. The election brought two new members to the board: David Ackerman and Caroline A. Lucas.

In years that do not include a presidential election, turnouts are usually much lower. In 2013, 2014 and 2015, for example, turnouts in the November elections were 25.4 percent, 46.3 percent and 29.49 percent, respectively.

In the 2016 election, the 210,661 voters (65 percent) who used mail-in ballots substantially exceeded the 165,877 voters (57 percent) who did so in 2012, according to Elections Office records.

Those opting for the tradition of voting at the polls dropped to 32 percent of ballots cast, a total of 105,014. Those numbers were 41 percent, or 119,212 ballots, in 2012.

The number of poll workers was also lower: about 1,700 this time compared with 1,876 in 2012. "We truly appreciate the outstanding men, women, and students who served our voters on Election Day," Mr. Church said. "Their commitment and professionalism was critical to the success of conducting the election."

• See official election results.

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