Psilocybin Decriminalization: A City-by-City Guide

Psychedelic Law & Policy

31.3M lifetime psilocybin users in the US by 2023

Lifetime psilocybin use rose from 25 million Americans in 2019 to 31.3 million in 2023 — a period overlapping exactly with the city-level decriminalization wave. The Rockhill 2025 Annals of Internal Medicine study tracked the trend across five national datasets.

Rockhill et al., Annals of Internal Medicine, 2025

2019

Denver passed ballot Initiative I-301 (50.6%) — the first US city to decriminalize psilocybin, triggering a cascade of city and state-level actions over the following six years

March 2025

Denver City Council formally repealed I-301 because Colorado's statewide Prop 122 had superseded it — the first city-level decrim law to be retired by statewide legalization

3 strength levels

City decriminalization policies differ significantly: lowest-priority resolutions are advisory; resource-prohibition measures are legally binding; state-level legalization supersedes both

Rockhill et al., Annals of Internal Medicine, 2025

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In May 2019, Denver voters passed Initiative I-301 by 50.6% and became the first US city to decriminalize psilocybin mushrooms. Six years and roughly two dozen jurisdictions later, psilocybin use among US adults had risen from 25 million lifetime users to 31.3 million, according to a 2025 analysis in Annals of Internal Medicine tracking five national datasets.^[1]

This article covers which cities and states have decriminalized psilocybin, what each type of policy actually does legally, and what data exists on the effects. For the broader context of why federal law makes city-level decriminalization necessary in the first place, the guide to psilocybin's Schedule I status covers the history.

What City Decriminalization Policies Actually Do — Three Levels of Strength

Not all decriminalization policies are equal, and understanding the difference matters for understanding what residents in each city can actually expect.

A 2023 JAMA Psychiatry analysis by Siegel and colleagues mapped the landscape of US psychedelic legislative reform, distinguishing three meaningfully different types of city and state action.^[2]

Level 1: Lowest-priority resolutions. The city council passes a symbolic statement declaring psilocybin prosecution the lowest enforcement priority. These are advisory, not binding. Police retain the legal authority to arrest for psilocybin possession — they are simply encouraged not to. Most city-level decrim policies fall into this category. The practical effect depends on how seriously local law enforcement interprets the resolution.

Level 2: Enforcement-resource prohibitions. A harder policy that legally prohibits spending city funds on psilocybin enforcement. Denver's 2019 ballot initiative and Washington DC's Initiative 81 both fit this model. Because they involve binding restrictions on how police resources are allocated, they have legal teeth that symbolic resolutions do not. Prosecutions become very unlikely because the city cannot fund them, even though federal law remains unaffected.

Level 3: State legalization. Oregon's Measure 109 and Colorado's Proposition 122 operate at a different level entirely. These create regulated frameworks for psilocybin access — licensed service centers in Oregon, licensed businesses and social clubs in Colorado — that supersede city-level measures. A city-level decrim law in a state with Prop 122 is now redundant.

This hierarchy explains why Denver's 2025 repeal of its 2019 ballot measure was not a defeat. It was the completion of a process. The city-level tool had served its purpose; the state-level framework replaced it.

The City-by-City Table

The table below covers US jurisdictions that have passed decriminalization measures or therapeutic access frameworks as of May 2026. Policy type follows the three-level taxonomy above. "Superseded" indicates a city measure replaced by stronger state action.

This table will be updated as new jurisdictions act. State-level therapeutic programs (Oregon, Colorado) are included for context but are a different policy category from city-level decriminalization.

Denver — The Ballot That Started a Movement, and Its 2025 Repeal

Denver's Initiative I-301 was not the first attempt to liberalize psilocybin policy in the United States, but it was the first to succeed at the ballot box. On May 8, 2019, Denver voters passed it by 50.6% — a margin of fewer than 2,000 votes. The narrowness was part of the point: it was a genuine democratic test, not a landslide, and it succeeded.

I-301 prohibited the city and county of Denver from spending funds on enforcement of laws criminalizing personal possession and use of psilocybin mushrooms by people 21 and over. It did not legalize sales. It did not create licensed facilities. It established, through a binding ballot measure, that the city's enforcement apparatus would not be pointed at adults possessing personal-use quantities.

Oakland followed three weeks later on June 4, 2019, with a unanimous city council vote that went further — decriminalizing not just psilocybin but all naturally occurring entheogenic plants. Washington DC's Initiative 81 passed in November 2020 with 76% of the vote, suggesting that in the right political context, decriminalization carried broad support.

The March 2025 repeal of Denver's I-301 by the city council is the most important and least-reported development in US psilocybin policy. The council did not reverse course on decriminalization. It formally retired a ballot measure that had become redundant. Colorado voters had passed Proposition 122 in November 2022, creating a statewide framework for regulated psilocybin access. Within that framework, Denver's 2019 ballot measure was obsolete. The city repealed it to avoid any legal ambiguity between city and state law.

This sequence is the intended trajectory for decriminalization advocacy: city-level action creates political cover and proof of concept, state-level action follows, and city measures are eventually replaced by something with more legal substance. Denver completed that arc.

The companion piece on Denver, Oakland, and beyond: the decriminalization wave covers the full narrative history of how the policy spread.

What Happened to Psilocybin Use After Decriminalization?

The Rockhill 2025 study in Annals of Internal Medicine is the most comprehensive analysis of US psilocybin use trends across the period of the decriminalization wave. Using five nationally representative datasets — NSDUH, MTF, NPDS, NHAMCS, and NMURx — the study tracked lifetime use, past-year use, and emergency indicators from 2019 through 2023.^[1]

Lifetime psilocybin use rose from 25 million Americans (10% of the population) in 2019 to 31.3 million (12.1%) in 2023. Past-year use increased 44% among adults aged 18-29 and 188% among adults 30 and older. Poison center calls involving psilocybin rose 201% in adults, 317% in adolescents, and 723% in children under 12 over the study period.^[1]

The children's figure warrants careful attention. A 723% increase in poison center calls involving children under 12 does not indicate that children were using psilocybin intentionally. It indicates that in homes where psilocybin was present — including as edibles or prepared products — young children were exposed by accident. This is the strongest empirical argument for the "against decriminalization" position and deserves honest acknowledgment.

Whether decriminalization caused the increase in adult use, or whether both decriminalization and increasing use reflect the same underlying shift in public opinion and availability, cannot be established from the Rockhill data alone. The correlation is real; the causation is contested.

Bhave and colleagues published the first peer-reviewed analysis specifically studying the effects of US city-level psilocybin decriminalization in the Journal of Psychoactive Drugs in 2025.^[3] Their analysis specifically examined what changed in jurisdictions that passed decriminalization measures — the closest available data to a controlled comparison.

One important piece of context for interpreting the use data: Johansen and Krebs analyzed more than 135,000 US adults in a nationally representative population study and found no association between lifetime psychedelic use and mental health problems, suicidal ideation, or need for psychiatric treatment.^[4] An increase in psilocybin use does not automatically translate into an increase in harm at the population level, though it does increase the need for poison control awareness in households with children and unsecured supply.

For a full analysis of the case for and against decriminalization with evidence on both sides, the companion piece on the arguments for and against psilocybin decriminalization covers the strongest versions of each position.

What Decriminalization Does Not Do — The Practical Limits

Readers looking for operational clarity about what decriminalization means in practice should understand what these policies do not change.

Psilocybin remains illegal to sell in every decriminalized city in the United States except in Colorado's licensed regulated facilities. Decriminalization of personal possession does not create a legal retail or cultivation market. Someone in a decriminalized city who wants to obtain psilocybin must do so through informal channels that carry their own risks — unknown potency, contamination, and the ongoing federal illegality of transactions.

Federal law applies regardless of city or state policy. The DEA and federal prosecutors retain the authority to act on psilocybin cases anywhere in the United States. In practice, federal prosecution of personal possession amounts is extremely rare, but the legal exposure is real.

Quality control does not exist in decriminalized jurisdictions without state-licensed therapeutic programs. Psilocybin purchased outside a regulated framework has no standardized dosing, labeling, or safety testing. This is the primary harm-reduction gap that decriminalization does not address and that therapeutic legalization models — Oregon, Colorado — are designed to fill.

The companion piece on decriminalization vs. legalization: what's the difference? explains the full policy spectrum from symbolic resolutions to Oregon's therapeutic service center model and Australia's prescription framework.

For the full city-by-city tracker including policy-strength ratings and current status, the companion piece psilocybin decriminalization city by city: a complete US tracker covers all known US jurisdictions in table format optimized for state-specific searches.

The Bottom Line

Roughly two dozen US cities and two states have enacted psilocybin decriminalization or regulated access since Denver's 2019 ballot initiative. Policies range from advisory lowest-priority resolutions to binding enforcement-resource prohibitions to statewide therapeutic legalization. Lifetime US psilocybin use rose from 25 million in 2019 to 31.3 million in 2023 during this period; poison center calls involving children under 12 rose 723%, while Johansen 2015's 135,000-person population study found no link between psychedelic use and mental health problems at the population level. Denver's city-level decriminalization law was formally repealed in March 2025 after Colorado's Prop 122 superseded it.

Frequently Asked Questions

What cities have decriminalized psilocybin mushrooms?

US cities and jurisdictions that have decriminalized psilocybin include Denver (CO, 2019 — city measure now superseded by statewide Prop 122), Oakland (CA, 2019), Santa Cruz (CA, 2020), Washington DC (2020), Ann Arbor and Detroit and Hazel Park (MI, 2020-2021), Somerville, Cambridge, and Northampton (MA, 2021), Minneapolis (MN, 2023), and Tacoma (WA, 2025). At the state level, Oregon passed therapeutic access legislation in 2022 and Colorado passed Proposition 122 in 2022 — these are stronger legal frameworks than city-level decriminalization. Psilocybin use rose from 25 million lifetime users in 2019 to 31.3 million in 2023 during this period (Rockhill et al., Annals of Internal Medicine, 2025).

What happened in Denver after psilocybin was decriminalized?

Denver's Initiative I-301 passed by 50.6% in May 2019 and prohibited city funds from being used to enforce psilocybin possession laws for adults 21 and over. The immediate effect was that local law enforcement stopped pursuing psilocybin possession cases. The broader effect was catalytic: Oakland decriminalized weeks later, then Santa Cruz, Washington DC, Ann Arbor, and cities across Michigan and Massachusetts followed. The Denver initiative was formally repealed by the city council in March 2025 — not as a policy reversal, but because Colorado's statewide Prop 122 (passed November 2022) had created a regulated access framework that superseded the city measure, making it redundant.

Is psilocybin legal in California?

Psilocybin is not legal statewide in California. Oakland passed a resource-prohibition decriminalization measure in June 2019 (unanimous city council) and Santa Cruz passed a lowest-priority resolution in 2020. In those cities, personal possession is extremely unlikely to result in prosecution, but sales remain illegal. Outside those cities, California state law classifies psilocybin as a controlled substance. Unlike Colorado and Oregon, California has not passed statewide regulated access legislation.

What is the difference between city decriminalization and state legalization?

City decriminalization changes enforcement priorities — police are directed to treat psilocybin possession as low or no priority — but does not create a legal market or quality-controlled supply. State legalization (Oregon's Measure 109, Colorado's Prop 122) creates a regulated framework: licensed service centers, safety standards, and supervised access for adults. City measures can be superseded by state action, as happened in Denver when Prop 122 rendered I-301 obsolete. A 2023 JAMA Psychiatry analysis by Siegel and colleagues documented this spectrum from symbolic resolution to therapeutic legalization as distinct policy types with meaningfully different legal effects.

Did Denver's psilocybin decriminalization cause more drug use?

Nationally, lifetime psilocybin use rose from 25 million Americans in 2019 to 31.3 million in 2023 — the same period as the city decriminalization wave. Whether city-level decriminalization caused the increase, or whether the same cultural shift drove both decriminalization and increasing use, cannot be determined from the available data alone. Bhave and colleagues' 2025 analysis is the only peer-reviewed study specifically examining decriminalization effects in US cities. Johansen and Krebs' 2015 analysis of 135,000+ US adults found no association between psychedelic use and mental health problems at the population level, providing context for interpreting the use increase.

Sources & References

1. 1RTHM-02169·Rockhill, Karilynn M et al. (2025). “The Rise of Psilocybin Use in the United States: A Multisource Observational Study..” Annals of internal medicine.Study breakdown →PubMed →↩
2. 2RTHM-01791·Siegel, Joshua S et al. (2023). “Psychedelic Drug Legislative Reform and Legalization in the US..” JAMA psychiatry.Study breakdown →PubMed →↩
3. 3RTHM-02058·Bhave, Ashutosh (2025). “Magic of the Mushrooms: Effects of Psilocybin Decriminalization..” Journal of psychoactive drugs.Study breakdown →PubMed →↩
4. 4RTHM-00696·Johansen, Pål-Ørjan et al. (2015). “Psychedelics not linked to mental health problems or suicidal behavior: a population study..” Journal of psychopharmacology (Oxford.Study breakdown →PubMed →↩