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History of Election Results for Ballot Issues


Overview of the Statewide Ballot Measure Process

Both the Colorado Constitution and state statutes are subject to amendment by legislatively referred and citizen-initiated measures. The process is governed by the Colorado Constitution and state law.1 

Legislatively referred measures.  The Colorado General Assembly may refer constitutional measures to the voters with a two-thirds vote of both houses, and may refer statutory measures to the voters with a majority vote of both houses. A constitutional measure requires 55 percent of the votes cast in an election to pass, except when a proposed measure repeals rather than changes part of the constitution, in which case a simple majority of votes is required.2   While the General Assembly has the authority to change the state statutes during legislative session, the Taxpayer’s Bill of Rights (TABOR) requires that proposed tax increases receive approval from voters in order to take effect. The General Assembly submitted its first measure to Colorado voters in 1880.

Citizen-initiated measures.  Any Colorado resident may place a constitutional or statutory measure on the ballot. To place a measure on the ballot, proponents must collect the number of signatures equal to 5 percent of the total number of votes cast for the Secretary of State at the previous general election. Additionally, to place a constitutional measure on the ballot, at least 2 percent of registered voters’ signatures in each of the state’s 35 senate districts are required. The constitutional measure must also receive at least 55 percent of all votes cast to pass, unless a proposed measure repeals rather than changes part of the constitution, in which case a simple majority of votes is required.3  The use of citizen-initiated measures for constitutional and statutory changes was voted into law in 1910 and became available in 1912.

Process for placing a citizen-initiated measure on the ballot.  The multi-step process for placing a citizen-initiated measure on the ballot includes the submission of a proposed initiative; a review and comment hearing on the proposal with the Office of Legislative Legal Services and the Legislative Council Staff; a hearing with the Title Board to set the single subject title; and verification of collected signatures by the Secretary of State.  These steps are outlined on the Secretary of State’s and the Colorado General Assembly’s websites.

Even- and odd-numbered year elections.  State law clarifies the types of proposals that may appear on a statewide ballot in odd-numbered years.  Odd-year election proposals are limited to state matters arising under TABOR. These types of proposals include a new tax, a tax rate increase, an extension of an expiring tax, a tax policy change directly causing a net revenue gain, and emergency taxes. They also include the creation of multiple-year fiscal obligations or debt, an increase in the assessment rate for a class of property, the weakening of a state limit on spending, and voter-approved revenue changes. State law does not limit the types of proposals that are eligible for the ballot in even numbered years.

Numbering and lettering for ballot measures.  Beginning in November 2010, statewide citizen initiated measures are numbered, while those that are legislatively referred are lettered. Table 1 provides further detail on the numbering and lettering schedule for statewide ballot measures.

Table 1
Ballot Measure Numbering and Lettering Schedule1
1 to 99
(Beginning with 60)
100 to 199
(Beginning with 100)
Legislatively Referred
A to Z
(Beginning with P)
AA to ZZ
(Beginning with AA)
Source:  Section 1-5-407, C.R.S.
Parenthetical notes indicate the number or letter used as a starting point in 2010.  As of the 2022 election, the last alphanumeric designations used are Amendment 78, Amendment F, Proposition 126, and Proposition II.

1Colo. Const. art. V, § 1 and Sections 1-40-101, et seq., and 1-41-101, et seq., C.R.S.
2Colo. Const. art XIX, § 2.
3Colo. Const. art. V, § 1.
4Section 1 41-102, C.R.S.

Statewide Ballot Measures from 1880 to 2023

The tables below provide information about statewide ballot measures from 1880 to 2023. Table 2 displays ballot measures by type, origin, and outcome. Table 3 classifies measures by category. 

Table 2
Statewide Ballot Measures by Type, Origin, and Outcome
Legislatively referred
Citizen-initiated/No vote2
Legislatively referred
Citizen-initiated/No vote2
Total Measures
Source:  Legislative Council Staff.
In some cases, constitutional measures include measures that are both constitutional and statutory.
2 ”Citizen-initiated/No vote" indicates rare instances where ballot measures appeared on the ballot but were withdrawn or later determined to have insufficient signatures. 
Referendums occur when citizens request a vote against any act or section of an act that contains a referendum clause and was passed by the legislature.  
A question is a proposition in the form of a question arising under TABOR without reference to specific state legislation or a specific amendment to the state constitution.
Table 3
Statewide Ballot Measures by Category1
Category* Total Adopted Rejected
Abortion 9 2 7
Agriculture and Livestock 7 2 5
Alcohol 11 4 7
Business and Labor 29 13 16
Children and Domestic Matters 4 1 3
Civil Rights 8 4 4
Criminal Justice and Public Safety 9 5 4
Drug Policy 7 4 3
Education 25 11 14
Elections 48 32 16
Energy and Utilities 14 4 10
Gaming 27 11 16
General Assembly 17 10 7
Government Finance  18 5 13
Health and Human Services 11 6 5
Housing 1 1 0
Initiative Process 14 7 7
Judiciary and Courts 23 14 9
Local Government 22 11 11
Natural Resources 11 4 7
Public Employee Compensation 16 5 11
Public Pension 7 2 5
Property 8 3 5
State Government 48 21 27
Taxation 77 29 48
Technical Amendments 11 10 1
Term Limits 13 6 7
Transportation 13 5 8
Total 508 232 276
Source:  Legislative Council Staff.
Ballot measures are categorized by the most appropriate category; however, many measures fit under multiple categories. 
Statewide Ballot Measures from 1880 to 2023
The Colorado Legislative Council Staff maintains an online database of statewide ballot measures dating back to 1880.
The Secretary of State’s Office also maintains an archive of election results dating back to 1902. This information is also presented in the form of a searchable database.

The effective date for bills enacted without a safety clause is August 7, 2024, if the General Assembly adjourns sine die on May 8, 2024, unless otherwise specified. Details