Contra Costa County, California
Your guide to voting in Contra Costa County, California: registration, sample ballots, ID requirements and where to get local help. Home to about 1,173,000 people, Contra Costa County ranks 9th in population among California's 58 counties. In California, each county elections office, often called the registrar of voters, handles registration, mails ballots and publishes the county voter information guide with your sample ballot.
Next Election
March 7, 2028
Voter Portal
Register Online
What's On My Ballot?
ID Requirements
Absentee / Early Voting
Registration Deadline
Register online or by mail at least 15 days before an election; conditional same-day registration is available after the deadline.
Why Voting Matters
Voting is how Contra Costa County residents shape the decisions made in their name. The next election for Contra Costa County voters is California's presidential primary on March 7, 2028; local elections can come sooner, so check your local election office. With health care and retail among the county's biggest employers, issues like health care costs are decided by the officials voters choose.
In the 2024 presidential election, about 529,000 ballots were cast in Contra Costa County, down about 9% from 581,000 in 2020. With roughly 927,000 adults living in the county, that is around 57% of adult residents, above the statewide rate of about 51%.
Around 398,000 adults here did not vote for president. Some aren't eligible, yet the rest are untapped power: one more voter in every 20 of them would mean about 19,900 extra Contra Costa County ballots, enough to change the result in many close contests.
Spread over about 717 square miles, Contra Costa County averages roughly 1,635 residents per square mile, one of the denser places in California. The county is home to about 3.0% of California's population.
ZIP codes in or partly in Contra Costa County include 94505, 94506, 94507, 94509, 94511, 94513, 94514 and 94516, plus 48 more. Confirm your registration, read through your sample ballot before Election Day, and choose whether you will vote early, by mail or in person. Invite someone you know in Contra Costa County to join you.
Voter Assistance Resources
Local election help in Contra Costa County: In California, each county elections office, often called the registrar of voters, handles registration, mails ballots and publishes the county voter information guide with your sample ballot. For registration, polling places, early voting and absentee ballots, contact the Contra Costa County elections office (registrar of voters).
Statewide directory, California Secretary of State's county elections offices list:
https://www.sos.ca.gov/elections/voting-resources/county-elections-offices
See your sample ballot. California county elections offices (your county mails and posts your sample ballot):
https://www.sos.ca.gov/elections/voting-resources/county-elections-offices
You can also preview a personalized ballot at Vote411.org.
Free, nonpartisan help is available before and on every Election Day: call or text the Election Protection hotline at 866-OUR-VOTE (866-687-8683). Spanish: 888-VE-Y-VOTA (888-839-8682). Asian languages: 888-API-VOTE (888-274-8683).
Voters with disabilities in Contra Costa County can ask for an accessible voting machine, curbside voting where offered, and help from a person of their choice. If you run into barriers, contact Disability Rights California, California's Protection and Advocacy agency, at (888) 569-7955. VoteRiders (844-338-8743) offers free help with voter ID.
Need a ride? Many local transit agencies and ride services offer free or discounted rides to the polls on Election Day, so check what is available before the next election. See our California voter page for statewide options. Details can change, so confirm with the official election office.
Military and overseas voters can get help from the Federal Voting Assistance Program at 1-800-438-VOTE (8683) or fvap.gov.
Sign up to be an election worker
Election workers (often called poll workers) keep voting running smoothly in Contra Costa County. Most are paid for their time, get free training, and help their neighbors cast their ballots. You can work a full day, a shorter shift, or help before Election Day. County and municipal election offices recruit and train their own workers, and the EAC's Help America Vote page links to yours. Find out how to sign up:
https://www.eac.gov/help-america-vote
Take the Next Step
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