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How Colorado Got Here

Colorado's election system wasn't built overnight. Its history spans more than a century of decisions by voters and their elected representatives about participation, citizen lawmaking and how ballots are cast and verified.

Today's model is the latest chapter in a much longer Colorado story.

Explore the story ↓ See the model today

Denver, 1916 · Library of Congress, National Woman’s Party records · Image via History Colorado · Cropped.

The short version

Milestones that shaped Colorado elections

Colorado expanded voting access while developing stronger ways to verify results and protect election systems. These milestones trace both parts of that story.

01

1787–88 | States shape election systems

The Constitution establishes state responsibility for congressional election rules alongside Congress’s authority to make or alter them. States build their election models, and state and local officials administer them.

02

1864–76 | Early foundations

Civil War soldiers vote away from home under state absentee-voting arrangements. At statehood in 1876, Colorado protects voting residency during military service.

Sources: Library of Congress: Voting in the Field; Colorado Constitution, Article VII, §4.

03

1893 | Voters expand suffrage

Colorado becomes the first state to approve women’s right to vote by popular referendum, 27 years before the 19th Amendment.

Sources: National Park Service: Colorado suffrage history.

04

1910–12 | Citizens shape the ballot

Colorado voters approve the initiative and referendum in 1910. Citizen initiatives become available in 1912, giving voters a way to propose laws and constitutional amendments by petition.

Sources: General Assembly: ballot-measure history.

05

1915 | Absentee ballots by mail

Colorado authorizes absent electors to vote by mail—nearly a century before statewide mail-ballot delivery.

Sources: Legislative index: 1915 absent-elector law.

06

1992–93 | Options and access expand

In 1992, legislators authorize no-excuse absentee voting and in-person early voting; voters approve TABOR. The federal National Voter Registration Act follows in 1993.

Sources: HB92-1004: 1992 legislative digest, pp. 50–51; Colorado Constitution, Article X, §20 (TABOR); History of the 1992 TABOR vote; U.S. Department of Justice: National Voter Registration Act.

07

2003–07 | Voters gain more choices

Larimer County introduces vote centers in 2003, followed by statewide authority in 2004. In 2007, permanent mail-in status lets voters choose ongoing mail-ballot delivery.

Sources: Larimer County: vote centers and SB04-153; SB07-234: 2007 legislative digest, pp. 61–62.

08

2009 | Access and verification advance

Colorado authorizes mail-ballot primaries and requires risk-limiting audits, laying the groundwork for checking reported election outcomes against paper ballots.

Sources: HB09-1015: mail-ballot primaries; HB09-1335: risk-limiting audit requirement.

09

2013 | Voter choice leads the way

By April 1, 70.9% of active voters have chosen permanent mail-in status. Later that year, legislators make mail-ballot delivery standard statewide, alongside in-person voting options.

Sources: April 1, 2013 registration statistics (Excel), PMIV Requests tab; HB13-1303: 2013 legislative digest.

10

2017 | Paper ballots verify outcomes

Colorado completes the nation’s first statewide risk-limiting audit. Election officials examine randomly selected paper ballots to test whether reported outcomes are correct.

Sources: U.S. Election Assistance Commission: first statewide risk-limiting audit.

11

2021 | Clerks propose integrity improvements

CCCA sets out an agenda for stronger signature audits, voter-list review, public access to election records and sustainable funding.

Sources: Read CCCA’s original June 29, 2021 recommendations (PDF).

12

2022 | Stronger controls protect election integrity and guard against insider threats

Colorado strengthens protections against insider threats with controlled access, video surveillance, restrictions on copying voting-system hard drives and stronger penalties for unauthorized access.

Sources: SB22-153: enacted security measures.

13

2025 | Stronger signature audits

More detailed statewide audit requirements strengthen the review of signature-verification decisions, advancing a safeguard CCCA proposed in 2021.

Sources: 2025 signature-audit rule adoption.

From early foundations to today's voting choices

How Colorado elections evolved

The timeline begins with the Constitution’s division of election authority, continues through national Civil War-era absentee voting, then follows Colorado’s own milestones: voting rights at statehood, women’s suffrage, citizen initiatives and absentee ballots by mail. Over the generations, voters and their elected representatives shaped who could participate, how citizens could influence the law, and how ballots were cast. Later changes expanded voting options and strengthened the records, audits and safeguards used to verify election results.

1787–88

States shape and administer elections. The Constitution defines federal authority.

First page of the United States Constitution, beginning with We the People and containing Article I.
The constitutional starting point, 1787. Article I, Section 4 assigns states responsibility for congressional election rules and authorizes Congress to make or alter them.
Image: National Archives · Public domain.
Read the Constitution →

States establish their election models.

Through their lawmaking processes, states determine how voters register, which voting options are available, how ballots are processed and counted, and how results are audited and certified—subject to the U.S. Constitution and applicable federal law. This gives states substantial authority to build election systems suited to their communities.

State and local officials put those laws into practice.

Local responsibilities vary by state but commonly include maintaining voter records, preparing and distributing ballots, staffing voting locations, processing returned ballots and counting votes. State officials provide statewide administration and oversight as state law directs. States establish their own election frameworks, and state and local officials carry them out.

Congress can establish binding federal election rules.

Article I, Section 4 assigns states the initial responsibility for regulating congressional elections, while expressly allowing Congress to make or alter those regulations. Congress also has authority to enforce constitutional voting-rights protections. Its authority is constitutionally defined and can override conflicting state laws.

The President has no independent constitutional authority to take over state election administration.

The executive branch carries out and enforces valid federal laws, including voting-rights laws. Those responsibilities must rest on lawful authority; they do not give the President general control over the states’ elections or power to rewrite election rules by decree.

“It was found impossible to fix the time, place, and manner, of the election of representatives, in the Constitution. It was found necessary to leave the regulation of these, in the first place, to the state governments, as being best acquainted with the situation of the people, subject to the control of the general government, in order to enable it to produce uniformity, and prevent its own dissolution.”
James Madison · Virginia Ratifying Convention · June 14, 1788

Madison explained the balance: states would set the initial rules for congressional elections because they understood local circumstances, while Congress retained authority to make or alter those rules. In this passage, the federal control he described was Congress’s authority under the Elections Clause.

Sources: U.S. Constitution, Articles I and II; U.S. Election Assistance Commission; DOJ: federal voting-rights protections; Madison, Virginia Ratifying Convention, June 14, 1788.

1864

National context: Civil War soldiers vote away from home

The Civil War brings widespread military absentee voting. For the 1864 election, states allow soldiers to vote away from home, including at polling places in the field. Absentee voting does not always mean voting by mail; these arrangements vary by state.

Source: Library of Congress, “Voting in the Field”.

William Waud’s 1864 drawing of Pennsylvania soldiers gathering to vote at an Army of the James camp.
Voting away from home. In 1864.William Waud’s drawing for Harper’s Weekly, October 29, 1864. Pennsylvania soldiers, Army of the James. National context.
View the original · Library of Congress ↗
1876

Military service does not erase voting residency

Colorado’s constitution protects a person’s voting residence during absence for military service. This residency protection does not itself establish a procedure for voting by mail.

Source: Colorado Constitution, Article VII, Section 4.

1893
Women installing a National Woman’s Party suffrage billboard in Denver in 1916.
Denver, 1916. Women installing a National Woman’s Party billboard during the campaign for national women’s suffrage, 23 years after Colorado’s referendum.
Library of Congress, National Woman’s Party records. Image via History Colorado · View catalog record.
1893 · A milestone decided by voters

Colorado voters approve women’s suffrage

In 1893, Colorado became the first state to approve women’s right to vote by popular referendum, 27 years before ratification of the 19th Amendment.

Source: National Park Service

1910

Citizens gain the initiative and referendum

Colorado voters approve a constitutional amendment allowing citizens to propose laws and constitutional amendments by petition for a public vote. Citizen initiatives become available in 1912.

This helps explain why Colorado ballots include policy choices alongside candidates. Measures can originate with citizens or be referred by the legislature. These measures add to ballot length and the reading voters need to do before making their choices.

Sources: Colorado General Assembly, history of ballot measures; Colorado Judicial Branch, ballot initiatives.

1915

Colorado authorizes absentee voting by mail

A law approved March 18, 1915, permits absent electors to vote by mail. Colorado’s use of mailed absentee ballots thus predates statewide mail-ballot delivery by nearly a century.

Source: 1923 legislative index identifying the 1915 act.

1984

Colorado voters approve motor-voter registration

Colorado voters approve Amendment 4, allowing eligible residents to register to vote when applying for a driver’s license. Colorado takes this step before Congress passes the federal “Motor Voter” law in 1993.

Sources: Colorado Secretary of State, 1984 Amendment 4; U.S. Department of Justice, federal motor-voter law.

1990

Colorado enacts the Mail Ballot Election Act

Colorado lawmakers pass SB90-97, allowing local governments to choose mail-ballot elections for nonpartisan candidates and ballot issues, subject to state oversight. The law excludes elections involving partisan candidates and elections held alongside, or on the same day as, primary, general or congressional vacancy elections. Approved in 1990 and effective in 1991, it establishes an early framework for conducting entire elections by mail.

Source: SB90-97, 1990 Colorado Session Laws, Chapter 43, pp. 314–318.

1992

Early voting and no-excuse absentee voting

Colorado already has a long history of absentee voting by mail. HB92-1004 removes the qualifying-reason requirement for absentee voting and authorizes in-person early voting for registered electors. Voters can request an absentee ballot without an excuse or vote early at a designated polling place.

The same year, Colorado voters approve TABOR, giving mail-ballot elections a larger role. TABOR requires public votes on specified tax increases and debt obligations. Colorado election law allows these fiscal questions to be decided through mail-ballot elections—giving voting by mail an important role in local decision-making long before statewide mail-ballot delivery begins in 2013.

Sources: HB92-1004: 1992 legislative digest, pp. 50–51; Colorado Constitution, Article X, §20 (TABOR); History of the 1992 TABOR vote.

1993

Early voting and election coordination develop further

HB93-1255 refines the procedures for casting, receiving, counting and challenging early and absentee votes, and requires accessible early-voting polling places. It also clarifies county clerks’ responsibility for coordinated elections and helps voters cast ballots for multiple jurisdictions at one polling place. Approved June 6, 1993, the law takes effect July 1, 1993.

Sources: 1993 legislative digest, HB93-1255, pp. 56–58; original act, 1993 Colorado Session Laws, Chapter 258.

1993

Federal NVRA expands voter registration

Congress enacts the National Voter Registration Act, often called “Motor Voter.” The federal law expands registration opportunities through motor vehicle agencies, mail applications and designated public agencies, while also establishing requirements for voter-list maintenance.

Sources: U.S. Department of Justice: National Voter Registration Act.

1996

Early-voting framework expands

HB96-1061 separates existing early-voting provisions and requires every county clerk to provide an early-voting polling place. It takes effect July 1, 1996.

Sources: HB96-1061: 1996 legislative digest.

2001–2002

Donetta Davidson helps lead Colorado’s election reforms

Following the 2000 presidential election, Secretary of State Donetta Davidson established a task force to identify potential problems in Colorado’s election process and recommend legislative solutions.

That work helped inform HB02-1307, which expanded provisional voting to precinct polling places, improved information sharing for voter-registration records and required signature checks on absentee-ballot envelopes.

2002

HAVA modernizes election administration

Following the 2000 presidential election, federal law brings new voting-system standards, accessibility requirements, provisional ballots, statewide registration-system requirements and the Election Assistance Commission.

Sources: U.S. Department of Justice: Help America Vote Act; Electionline: Colorado’s 2002 reforms.

President George W. Bush signs the Help America Vote Act at a ceremony on October 29, 2002.
2002: The Help America Vote Act becomes law.President George W. Bush signs HAVA on October 29, 2002. Official White House photograph by Paul Morse.
View the photograph in the White House archive →
Read the original signing announcement →
2003–04

Vote centers emerge

Larimer County uses vote centers in its 2003 coordinated election. SB04-153 establishes statewide authority for counties to use the model in 2004.

2007

Permanent Mail-In Voting

SB07-234 establishes the Permanent Mail-In Voter framework. Eligible voters can choose permanent mail-in status so they continue receiving mail ballots without making a new request election after election.

Sources: SB07-234: 2007 legislative digest, pp. 61–62.

2009

Mail-ballot primaries + risk-limiting audits

HB09-1015 authorizes mail-ballot primary elections. HB09-1335 also establishes the statutory requirement for risk-limiting audits, later implemented statewide in 2017.

Sources: HB09-1015: mail-ballot primaries; HB09-1335: risk-limiting audit requirement.

2009–10

Federal MOVE Act strengthens voting for military and overseas citizens

Congress expands UOCAVA through the Military and Overseas Voter Empowerment Act. Among its major changes, states must provide electronic options for receiving registration and ballot materials and transmit validly requested absentee ballots to covered voters at least 45 days before federal elections when the request is received by that deadline. Most requirements take effect for the 2010 election cycle.

Sources: Justice Department: MOVE Act implementation; Justice Department: UOCAVA requirements.

2010

Online voter registration

Colorado launches online voter registration, adding another way for eligible voters to maintain their registration.

Sources: Department of State: FY2014–15 strategic plan, online registration history.

2012

Colorado helps launch ERIC

Under Secretary of State Scott Gessler, Colorado becomes one of seven founding states of the Electronic Registration Information Center (ERIC) in 2012. The bipartisan, multistate initiative uses registration and motor-vehicle data to help election officials identify outdated and potentially duplicate voter records.

Sources: ERIC: founding states and list-maintenance work.

What is ERIC?
It helps election officials identify outdated and potentially duplicate records while Colorado retains control over every voter-record decision.

The Electronic Registration Information Center helps states spot voter records that may be outdated or inaccurate by securely comparing official data across participating states. Colorado was one of the bipartisan group of seven states that created ERIC in 2012.

01Cross-state movers

Finds voters who appear to have moved from one member state to another.

02In-state updates

Finds newer address or contact information in motor-vehicle records.

03Duplicate records

Flags registrations in the same state that may belong to the same person.

04Deceased voters

Compares voter records with official Social Security death data.

ERIC provides leads. Election officials verify and act.

Step 1States send protected data
Step 2ERIC compares official records
Step 3Possible matches are returned
Step 4Officials validate under law
Key guardrail: ERIC is never connected to Colorado's voter registration system and cannot add, remove, or change a voter record. Colorado retains control of its voter rolls, verifies the information ERIC provides, and follows federal and state law before updating a record. Sensitive identifiers are cryptographically hashed before transmission, and member states cannot see one another's data or reports.

ERIC also produces voter-participation reports that can flag possible voting in more than one member state or on behalf of a deceased voter. Those are leads, not findings of guilt. Election officials review the underlying records and refer credible cases to law enforcement. Colorado rules also require counties that receive interstate information indicating possible voting in more than one jurisdiction to send the information to the Secretary of State for possible investigation and prosecution. Since 2013, ERIC reports have identified millions of potentially outdated records for member states. Read ERIC's FAQ, security overview, published statistics, and Colorado Election Rule 2.

2013
HB13-1303 · Voter Access and Modernized Elections Act

Mail-ballot delivery, vote centers and same-day registration

The act made mail-ballot delivery standard for active registered voters, preserved in-person voting through Voter Service and Polling Centers, and added same-day registration. It brought these options together into the foundation of Colorado’s modern hybrid election model.

Sources: HB13-1303: 2013 legislative digest.

A milestone, not a starting line

70.9%

of Colorado’s active voters had chosen permanent mail-in voter status as of April 1, 2013, before HB13-1303 passed.

The act built on choices Colorado voters were already making.

Source: Colorado Secretary of State, April 1, 2013 registration statistics (Excel), PMIV Requests tab.

What did HB13-1303 change? +

Mail-ballot delivery: Active registered voters receive a ballot by mail.

In-person voting: Voter Service and Polling Centers preserve a robust in-person option for voters who want or need it.

Same-day registration: Eligible Coloradans can register and vote in person through Election Day.

A statewide model: The law brought together practices Colorado had been developing for years, including mail voting and vote centers, into the foundation of today's hybrid election model.

2015

Counties pilot a uniform voting system

Eight Colorado counties test equipment from four vendors during the November 2015 election. The Pilot Election Review Committee (PERC) examines the pilot experience and hears from vendors as Colorado evaluates options for a more uniform voting system.

Clear Ballot is piloted in Adams and Gilpin counties; Dominion in Denver and Mesa; ES&S in Jefferson and Teller; and Hart InterCivic in Douglas and Garfield. The trials bring practical experience from voters, election judges and county staff into the selection process.

2016–18

Unaffiliated voters enter party primaries

Voters approve Propositions 107 and 108 in 2016. Implementation legislation follows in 2017, and unaffiliated voters begin participating in major-party primaries under the new model in 2018.

Sources: SB17-305: 2017 implementing legislation and rules; Secretary of State: 2018 unaffiliated-primary announcement.

2017

Election infrastructure designated as critical infrastructure

On January 6, 2017, U.S. Department of Homeland Security Secretary Jeh Johnson designates election infrastructure as critical infrastructure during the Obama administration. The designation gives election officials priority access to federal security assistance and strengthens coordination and threat-information sharing.

For Colorado and other states, the designation supports security cooperation while election administration remains under state and local control. Participation in federal assistance is voluntary.

2017

First statewide risk-limiting audit

Colorado becomes the first state to complete a statewide risk-limiting audit, using paper ballots to statistically test reported outcomes.

2017–20

Automatic voter registration develops

Colorado introduces front-end automatic voter registration at the DMV in 2017. Legislation expands the system in 2019, and back-end automatic registration begins in 2020.

Sources: Grimmer and Rodden: Colorado’s AVR stages, section 3; SB19-235: automatic registration expansion.

What changed with AVR? +

The work began before implementation. Colorado election officials and state partners had been examining Motor Voter and registration modernization for several years before the 2017 changes.

2017: Front-end automatic voter registration begins in February, using a DMV prompt and follow-up questions.

2019: SB19-235 expands automatic voter registration through electronic transfers of qualifying records.

2020: Back-end automatic registration begins, with a later opportunity to opt out.

The broader trend predates AVR: Colorado already had a substantial unaffiliated electorate before automatic voter registration. AVR arrived amid longer-running changes in party registration rather than marking the beginning of those changes.

See the registration trend +

Active registered voters by affiliation

0 500K 1.0M 1.5M 2.0M 2010 2020 2026 2017 Front-end AVR November 1, 2010 — Unaffiliated: 771,325 November 1, 2020 — Unaffiliated: 1,541,199 September 1, 2026 — Unaffiliated: 2,034,154 November 1, 2010 — Democratic: 812,389 November 1, 2020 — Democratic: 1,129,733 September 1, 2026 — Democratic: 987,582 November 1, 2010 — Republican: 874,962 November 1, 2020 — Republican: 1,028,239 September 1, 2026 — Republican: 887,577
━ Unaffiliated (solid) ┄ Democratic (dashed) ··· Republican (dotted) ┄· Other parties (dash-dot)

Chart figures in text

November 1, 2010: Unaffiliated 771,325; Democratic 812,389; Republican 874,962.

November 1, 2020: Unaffiliated 1,541,199; Democratic 1,129,733; Republican 1,028,239.

September 1, 2026: Unaffiliated 2,034,154; Democratic 987,582; Republican 887,577.

Other party affiliations total 18,526 in 2010, 68,065 in 2020, and 97,136 in 2026. These totals combine every reported affiliation other than Democratic, Republican and unaffiliated. The vertical marker identifies front-end automatic voter registration in 2017.

Source: Colorado Secretary of State, Party & Status tabs, active statewide totals: November 1, 2010 (XLS); November 1, 2020 (XLSX); September 1, 2026 (XLSX).

The graph shows chronology, not causation. The 2017 marker identifies front-end AVR; expansion legislation followed in 2019 and back-end AVR began in 2020.

2018

National attention for Colorado's security model

The Washington Post publishes “How Colorado became the safest state to cast a vote,” highlighting paper ballots, audits and election-security practices.

Read the Washington Post article →

2021

CCCA proposes an election-integrity improvement agenda

In a June 29 letter to the Bipartisan Election Advisory Committee, CCCA recommends stronger signature-verification audits, review of voter-list maintenance, public access to ballot images and cast vote records at no cost with protections for voter anonymity, and modernized election funding.

Led by CCCA, this initiative brings together representatives from the Colorado Secretary of State’s office, national election experts and other stakeholders focused on improving Colorado elections.

Signature-audit enhancements and funding modernization have since been achieved. Work continues on other initiatives, and CCCA’s agenda has expanded to enhancements to the risk-limiting audit—improving its transparency, clarity and usefulness while preserving rigorous verification of reported election outcomes.

Sources: Read CCCA’s original June 29, 2021 recommendations (PDF).

Sources: Signature-verification audit requirements; Election funding modernization, SB23-276.

2022
SB22-153 · Internal Election Security Measures

Stronger controls protect election integrity and guard against insider threats

The act required controlled key-card access and video surveillance for voting-system storage, restricted unauthorized copying of voting-system hard drives, and strengthened penalties for unauthorized access and disclosure of confidential voting-system information.

Alongside election rules, these changes strengthened Colorado’s protections against insider threats. The broader safeguards include background-check requirements, trusted-build procedures, security seals and controls on administrative privileges.

Read the enacted SB22-153 summary →

What changed? +
ACCESS

Stronger controls over who can access voting equipment and secure areas.

ACCOUNTABILITY

Background checks, documented privileges and tighter administrative access, along with stronger election offenses and penalties for unauthorized access, disclosure of protected voting-system information, and other violations of election law.

PHYSICAL SECURITY

Video surveillance, seals and custody requirements.

RISK MANAGEMENT

Resources and ongoing assessments to help counties strengthen election security.

The principle: No individual should have unchecked access to critical election systems.

2023

Colorado modernizes how elections are funded

As Colorado's election system became more sophisticated, the cost of administering it changed too. SB23-276 replaced the longstanding per-active-voter reimbursement approach with a model tied more closely to actual election costs.

Sources: SB23-276: enacted election legislation.

45%

The state's share of necessary and reasonable county election costs for elections with state-certified ballot content under the new reimbursement model.

Modern elections require sustainable funding for staffing, equipment, facilities, ballot processing, security and other election operations.

2025

Stronger signature-verification audits

Colorado strengthens signature-verification audit requirements, advancing a safeguard CCCA called for in 2021.

See how signature verification is checked today →

Sources: December 22, 2025 rule adoption; Current Election Rule 7.7.8.

An important distinction

Colorado is a mail-ballot delivery state, not simply an “all-mail” state.

Every active registered voter receives a ballot by mail, but every voter also has access to in-person voting through Voter Service and Polling Centers.

MAIL-BALLOT DELIVERY

Active registered voters receive ballots automatically and can return them by mail or at a ballot drop box.

IN-PERSON VOTING

Voters can instead visit a VSPC to register or update their registration, obtain a replacement ballot, receive assistance or vote in person.

Colorado's modern model is hybrid by design: broad mail-ballot delivery plus robust in-person voting.

The Colorado model today

Access evolved. So did security.

DELIVERActive registered voters receive a ballot.
CHOOSEVote that ballot or vote in person.
VERIFYMail-ballot signatures are verified.
PROTECTBallots, systems and facilities are secured.
RECONCILEOfficials account for ballots and participation.
AUDITPaper ballots independently test reported outcomes.

And the infrastructure around those steps continues to evolve: Colorado has added stronger insider-threat protections and modernized how the state shares the cost of administering elections with counties.

GO DEEPER · SECURITY See the safeguards, checks and evidence behind each step. Explore Election Defense in Depth →
The story continues

The Colorado model is still evolving.

Colorado's election system has never been static. For more than a century, voters and their elected representatives have shaped participation, citizen lawmaking and voting options. More recent changes have expanded registration access and strengthened ballot verification, audits and election security.

Many of those changes followed something equally important: how Colorado voters were already choosing to participate.
Keep exploring

Three pages. One Colorado election story.

How We Got Here

Why Colorado's system developed this way.

YOU ARE HERE

How Colorado Secures Your Vote

See the safeguards that protect ballots, systems and results.

Explore election security →

Voting in the 2026 Election

Dates, deadlines, voting options and official information.

Get ready to vote →
Historical sources

Explore the original records behind these milestones.