Thirty years ago -- back when they were called "absentee ballots" -- only about 6 percent of people in Contra Costa County mailed in their votes. Now, more than half mail their ballots, and many of those won't be counted until after the election, which could change the outcome of some close races.
County Clerk Steve Weir said Danville and San Ramon will likely be among the spots with more than 60 percent mailed in.
"They probably have a higher percent of residents that vote by mail," Weir said.
He said people who mail in ballots generally have a higher income, own their own homes, are more educated, older and are more civicly involved -- traits that San Ramon and Danville residents share, to a greater or lesser degree.
State law allows mail-in ballots to be opened seven business days before the election, and Weir's staff has been doing so since Oct. 22.
Because of the multiple-stage process it takes to count and validate all those ballots, he said it's likely some 25 percent won't be tallied until after Tuesday and won't be released before Friday.
"It's a really big deal because they've gone from being a system for people being disabled or out of the area," Weir said. He added that with a smaller turnout, as expected in this election, those mailed-in ballots will have a bigger impact.
He said the ballots come in waves, broken down by date; traditionally, Conservatives mail in their ballots in the first or second wave, while Democrats and undecideds take longer, which could turn the tide as those later ballots are checked, validated and counted.
Weir said the percentage of mail-in ballots has been climbing, from 5.9 percent in 1980 to nearly 10 percent in 1986.
That number jumped to 22 percent in 1994, and by 2002, it was 34 percent, and still -- legally, anyway -- was solely for the disabled and those out of the area on Election Day.
That, Weir said, was when state officials sanctioned what was already going on.
"The state said, 'You know, if anyone wants to vote absentee permanently, it's open to everybody,'" he said.
Weir said despite the climbing number of mail-in votes, state officials aren't planning on consolidating any precincts.
"They want people to have the ease of going to their local polling place," he said.