According to a press release from Office of Secretary of State, dated Oct. 8, 2012:
While Election Day is still weeks away, October 8 marks the start of “election month,” when county elections officials prepare to mail November 6 General Election ballots to the millions of Californians who opt for the convenience of voting by mail.
“With the ever-increasing popularity of voting by mail, Election Day has really become election month,” said Secretary of State Debra Bowen, the state’s chief elections officer. “Voting by mail lets you vote when you decide it’s convenient because you can mark your ballot and mail it now, or mark it as you make up your mind on issues and candidates. Whatever you do, make sure your county elections official receives your ballot by 8:00 p.m. on Election Day so it will be counted.”
Any California voter may vote by mail. The last day to request a vote-by-mail ballot is October 30. A registered voter may request a ballot by using the application printed on the back of the sample ballot booklet mailed by the county elections office, or obtain an application online at: www.sos.ca.gov/elections/vote-by-mail/pdf/fill-in-vote-by-mail-app-instruct.pdf. Registered voters can also vote in person at their county elections office prior to November 6.
County elections officials will begin mailing vote-by-mail ballots as early as October 9 (post offices are closed today for a federal holiday). Ballots have already been mailed to military and overseas voters. Vote-by-mail voters can cast their November 6 ballots through the mail, drop them off at any polling place within the voter’s county, or vote in person at county elections offices. Once county elections officials determine the signature on the vote-by-mail ballot return envelope matches the voter’s signature on his or her voter registration application, and the voter did not vote elsewhere in the same election, the ballot is counted. All valid vote-by-mail ballots are counted in every election, regardless of the outcome or closeness of any race.
Vote-by-mail ballots comprised 65 percent of ballots cast in the June 2012 primary – the most ever in a California statewide election.