Jefferson County, Colorado
Everything a Jefferson County, Colorado voter needs in one place: registration, voter ID, absentee and early voting, and your sample ballot. Home to about 579,000 people, Jefferson County ranks 4th in population among Colorado's 64 counties. In Colorado, the county clerk and recorder runs elections, mails every active voter a ballot and staffs voter service centers.
Next Election
March 21, 2028
Voter Portal
Register Online
What's On My Ballot?
ID Requirements
Absentee / Early Voting
Registration Deadline
Register online or by mail at least 8 days before an election; same-day registration is available in person, but registering early helps you get your ballot by mail.
Why Voting Matters
Every eligible adult in Jefferson County, Colorado holds the same power on Election Day: one vote that counts exactly as much as anyone else's. The next election for Jefferson County voters is Colorado's 2028 presidential primary, on a date the governor will set no later than March 21, 2028, though a statewide ballot issue could come first on November 2, 2027; local elections can come sooner, so check your local election office. Many Jefferson County jobs are in retail and health care, so decisions about local businesses and health care costs hit close to home.
In the 2024 presidential election, about 362,000 ballots were cast in Jefferson County, down about 4% from 377,000 in 2020. With roughly 473,000 adults living in the county, that is around 76% of adult residents, above the statewide rate of about 68%.
Around 112,000 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 5,590 extra Jefferson County ballots, enough to change the result in many close contests.
Across about 764 square miles, Jefferson County averages around 757 people per square mile, mixing neighborhoods, towns and open land. The county is home to about 9.7% of Colorado's population.
ZIP codes in or partly in Jefferson County include 80001, 80002, 80003, 80004, 80005, 80006, 80007 and 80020, plus 35 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 Jefferson County to join you.
Voter Assistance Resources
Local election help in Jefferson County: In Colorado, the county clerk and recorder runs elections, mails every active voter a ballot and staffs voter service centers. For registration, polling places, early voting and absentee ballots, contact the Jefferson County clerk and recorder.
Statewide directory, Colorado Secretary of State's county clerk roster:
https://www.coloradosos.gov/pubs/elections/Resources/files/CountyClerkRosterWebsite.pdf
See your sample ballot. Go Vote Colorado:
https://www.coloradosos.gov/voter/pages/pub/home.xhtml
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 Jefferson 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 Law Colorado, Colorado's Protection and Advocacy agency, at (303) 722-0300. 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 Colorado 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 Jefferson 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
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