Colorado cannabis history

Reviewed October 24, 2026

Colorado voters put adult-use marijuana into the state constitution in 2012. Licensed retail stores opened in January 2014. Medical marijuana was already in the constitution before that vote. This page stays with dates and documents that state offices publish, and it does not include a vote percentage the Secretary of State’s contest page did not show.

This is a short history, not legal advice. The rules that apply today are on the Colorado cannabis laws page.

At a glance

2000: medical use was already in the constitution

1. November 2000Voters adopted Amendment 20. The Secretary of State’s adopted-rules filing for the later retail rules describes that vote: Amendment 20 added article XVIII, section 14, and authorized medical marijuana. Adult-use sales in 2014 were a second constitutional section, not the start of all legal marijuana in Colorado.

2012: Amendment 64

1. November 6, 2012Amendment 64 was a statewide ballot question. The Secretary of State’s historical election record for contest 5116 is the official page for that question. This history does not reprint a yes-vote percentage, because that contest page did not include the vote totals.
2. December 10, 2012The same Secretary of State rules filing states that Amendment 64 was proclaimed into the Colorado Constitution on December 10, 2012. It is article XVIII, section 16. The constitution says the personal-use section takes effect upon that proclamation.
3. December 10, 2012Section 16 allows adults 21 and older to possess one ounce or less, to grow a limited number of plants in an enclosed locked space, and to transfer one ounce or less without payment to another adult 21 or older. It also tells the state to license stores and lets localities prohibit stores. Those rules are summarized, with citations, on the laws page.

2014: the first retail sales

1. January 1, 2014Retail marijuana sales started on January 1, 2014. A Colorado General Assembly publication on 2014 state marijuana taxes uses that date. The Department of Revenue’s marijuana sales reports say sales started in January 2014.
2. January 2014The constitution had told the state to begin accepting store-license applications on October 1, 2013, and it described January 1, 2014 as the point by which the licensing department was expected to have issued licenses if it had adopted rules and accepted applications. The sales reports are what show that retail sales actually began that month.
3. 2014The first $40 million collected each year from the constitutional excise tax is directed to public-school capital construction (article XVIII, section 16). The tax design is on the laws page, not restated here as a current rate sheet.

Sources

• Colorado Secretary of State, adopted rules filing 2013-00750 (PDF). States that Amendment 20 was adopted in November 2000 as article XVIII, section 14, and that Amendment 64 was proclaimed into the constitution on December 10, 2012.
• Colorado Secretary of State, historical election data, contest 5116. November 6, 2012 ballot question. Vote totals were not on that page, so none are stated here.
• Colorado Constitution article XVIII, section 16, as published by FindLaw, current as of January 1, 2025. Effective upon proclamation; license applications from October 1, 2013; the January 1, 2014 licensing clause.
• Colorado General Assembly, “State taxes on marijuana, 2014.” Retail sales on January 1, 2014.
• Colorado Department of Revenue, marijuana sales reports. “Sales started January 2014.”
• cannabis.colorado.gov, “Laws about cannabis use.” The state’s own summary of the 2012 vote and the retail rules.