The data on this page is updated monthly on the 1st of the month*.

Note that the voter counts reflected above do include a small percentage of voters who are under 18 at present, but may be eligible to vote by the next election. Colorado law allows residents to register to vote as young as 16. Only active voters who are age 18 on or before Election Day will be mailed a ballot. Note that periodically in Colorado a new qualified political organization becomes recognized, such as the Center Party or No Labels Party. Voters could register with these organizations only after these parties became recognized (a process handled at the state level). If data is not listed for a party, they likely were not a registration option at that time.

To get the most up-to-date voter registration counts for active voters or to search breakdowns of active voters by city, gender, age, and party use our Voter Registration Counts tool.

Return to Maps & Data to see voter registration data from previous election years.

Active voters automatically receive a mail ballot in each election. An active voter is:

• Someone who is registered to vote and whose confirmation card or previous mail ballot was not returned as undeliverable.
• Someone who is registered to vote and has not been identified as having moved to a different state.
• Someone who has recently registered or updated their voter registration since the last general election.

These voters do not automatically receive a mail ballot in each election. They are still eligible to vote by visiting a Voter Service and Polling Center during election time, or they can contact the Elections Division to find out more information about how to reactivate their record. Categories include:

• Undeliverable Ballot or Returned Mail: Voters who no longer reside at the address provided on their voter registration file. Official election correspondence and/or ballot has been returned to the clerk’s office as “undeliverable” by the post office because the resident no longer lives at the address.
• NCOA (National Change of Address database): Voters who have provided the U.S. Postal Service with new residence addresses that indicate they have moved out of the state of Colorado.

* This Voter Registration Data application was launched in October 2017. Data populated in earlier months in 2017 is approximately from the 1st of every month depending on whether the date fell on a weekday.