Ask how many Americans hold a medical marijuana card and no federal agency can tell you. There is no national registry. Every state keeps its own ledger: some publish it monthly, some release numbers only on request, and the most populous state does not require patients to sign up at all. For about a decade, the closest thing to a national count has come from a research team at the University of Michigan that collects those state ledgers one by one and adds them up.
The team’s newest count appeared on September 29, 2026, in Annals of Internal Medicine as two companion research letters: Trends in U.S. Medical Cannabis Registrations and Reasons for Use, 2016 to 2024 and U.S. Authorizing Clinicians and Medical Cannabis Caregivers: 2020–2024. Both are led by Kevin F. Boehnke of the University of Michigan Medical School. The data run through 2024, which makes them the most recent peer-reviewed national figures available this year. The letters themselves are paywalled, so the national totals below are the ones released by the journal’s publisher, the American College of Physicians (one summary on patient enrollment, one on clinicians and caregivers), while the background detail comes from the same team’s earlier open-access papers.
Key Takeaways
About 3.9 million people were registered in state medical cannabis programs in 2024, up from about 747,000 in 2016, an increase of more than 420 percent. That growth has leveled off, and enrollment often falls once a state opens adult-use sales. More than 35,000 clinicians were authorized to approve patients in 2024, compared with about 29,500 in 2020. For the first time the researchers also counted registered caregivers: nearly 110,000 nationwide, roughly three for every authorizing clinician. Chronic pain remains the most common reason people register, while registrations for PTSD and anxiety have grown substantially even though the evidence that cannabis helps those conditions is limited. Every one of these totals is assembled from uneven state records and should be read as the best available estimate, not as an exact census.
US Medical Marijuana Patients Statistics at a Glance
The table gathers the national figures in one place. Patient, clinician and caregiver counts are for 2024; the legal map is as of June 2026.
| Measure | Figure | Year |
|---|---|---|
| Registered medical cannabis patients | about 3.9 million | 2024 |
| Registered patients at the start of the series | about 747,000 | 2016 |
| Growth in registered patients | more than 420% | 2016 to 2024 |
| Clinicians authorized to approve patients | more than 35,000 | 2024 |
| Authorizing clinicians at the start of the series | about 29,500 | 2020 |
| Registered caregivers | nearly 110,000 | 2024 |
| Caregivers per authorizing clinician | roughly 3 to 1 | 2024 |
| States with legal medical cannabis | 41 plus Washington, DC | June 2026 |
| States with legal adult-use cannabis | 24 plus Washington, DC | June 2026 |
The state counts in the last two rows are the ones the authors themselves cite, from the National Conference of State Legislatures.
A useful cross-check exists outside academia. The Marijuana Policy Project, an advocacy group, keeps a running state-by-state tally that currently lists more than 3.69 million patients. It carries its own warning: the figure is partial and leaves out or undercounts several states, California among them. Two independent counts landing in the same range, both labeled incomplete, is a fair summary of how much is known.
How the Patient Count Grew and Then Flattened
The Michigan series now spans three papers, and read together they show a steep climb followed by a plateau.
The first paper covered 2016 to 2020 and found enrollment more than quadrupling, from 678,408 to 2,974,433 patients. The steepest rise was in Oklahoma, whose program opened in 2018: by 2020 the state had 927.1 patients per 10,000 residents, or roughly one resident in eleven.
The second paper covered 2020 to 2022 and counted 4,132,098 patients in 2022, a 33.3 percent rise in two years. Measured against population, that was 215.2 patients per 10,000 people.
The new letter extends the line to 2024 and reports about 3.9 million. The publisher’s summary describes enrollment as having leveled off as recreational access expanded. The totals in the three papers are not perfectly comparable, because each update depends on which states released data and the 2016 starting point itself differs between the first paper and the newest one. The cautious reading is a plateau, not a precisely measured decline.
Why Registrations Fall Where Adult-Use Stores Open
The pattern behind the plateau was already visible in the 2022 data. Of 15 jurisdictions that had adult-use laws in effect, 13 lost medical patients between 2020 and 2022. Arizona is the clearest case: 295,295 registered patients in 2020 and 129,836 in 2022, after adult-use sales began in 2021.
The researchers offered three explanations in that paper. Some people no longer need a medical card as legal cover for use that was never medical. Some drop out because of licensing fees or the inconvenience of certification visits. And some keep using cannabis for a health reason but simply buy it in an adult-use store. The third group matters most for anyone reading these statistics: a falling registry does not necessarily mean fewer people are using cannabis as medicine. It means fewer of them are visible.
“These findings indicate the growing use of cannabis for medical purposes, but also that adult use laws may decrease rates of patient enrollment,” Boehnke said when the 2022 data were published, in a University of Michigan release.
State dashboards tell the same story at close range. New Jersey’s medical enrollment peaked at 129,369 patients in May 2022, shortly after adult-use sales opened; as of September 15, 2026, the state’s Cannabis Regulatory Commission listed 42,984 patients and 2,802 caregivers.
What Patients Register For: Pain First, Mental Health Rising
Chronic pain has been the leading reason for a medical cannabis card for as long as states have published the data, and the new letter confirms it still is. What has changed is the mix behind it. According to the publisher’s summary, registrations for mental health conditions such as posttraumatic stress disorder and anxiety grew substantially over the study period.
The last fully published breakdown, for 2022, put chronic pain at 48.4 percent of patient-reported qualifying conditions, anxiety at 14.2 percent and PTSD at 13.0 percent.
This shift matters because the three conditions do not stand on equal evidence. The benchmark the Michigan team uses is the 2017 report of the National Academies of Sciences, Engineering, and Medicine, which found substantial or conclusive evidence of benefit for only three uses: chronic pain in adults, nausea and vomiting caused by chemotherapy, and muscle spasticity in multiple sclerosis. By that yardstick, the share of registrations tied to a well-supported condition fell from 70.4 percent in 2020 to 53.8 percent in 2022. The new letter’s conclusion, as summarized by the publisher, is that a growing share of patients use medical cannabis for conditions with less evidence behind them, and that more research on benefits and risks is needed.
That does not mean cannabis fails for those conditions. It means the question is still open, and recent trials point in different directions: a Lancet study questioned its effectiveness for anxiety, a Berlin trial of dronabinol for PTSD nightmares reported benefit for some patients, and on the pain side a 10-year study of 1,000 patients with chronic low back pain looked at what happens over the long term.
Authorizing Clinicians: Who Signs the Certifications
Headlines often say “doctors,” but the accurate term is authorizing clinicians, and the difference is real. In the team’s 2022 profile, 53.5 percent held an MD or DO degree, 34.4 percent were nurse practitioners and 11.0 percent were physician assistants. Where a specialty was recorded, family or internal medicine accounted for 63.4 percent, followed by physical medicine and rehabilitation at 9.1 percent and anesthesia or pain medicine at 7.9 percent.
The second distinction is between authorizing and prescribing. As the new letter puts it, clinicians can authorize medical cannabis access under state law, but they cannot prescribe the products, because nothing sold by cannabis retailers has been approved by the U.S. Food and Drug Administration. A certification opens the door to a dispensary; it does not specify a drug, a dose or a schedule the way a prescription does.
Nationally, the number of these clinicians rose from about 29,500 in 2020 to more than 35,000 in 2024. Their distribution is strikingly uneven. In 2022 there were 7.7 authorizing clinicians for every 1,000 registered patients overall, but the range ran from 0.8 per 1,000 in Oklahoma to 109 per 1,000 in Mississippi. States that also allow adult use had about twice the density of medical-only states that year: 12.9 per 1,000 patients against 6.1.
Caregivers: The First National Count
The genuinely new number in this release is the caregiver count. Caregivers, in the letter’s definition, are people without medical training whom state laws authorize to grow and possess cannabis for registered patients; the publisher’s summary describes them as individuals who help patients obtain, grow or manage cannabis products. Until now nobody had added them up nationally.
The total for 2024 is nearly 110,000, about three times the number of authorizing clinicians. Caregiver rates were highest in states that allow home cultivation and in states with adult-use programs. The authors conclude that both clinicians and caregivers are important parts of the medical cannabis system, and that the wide variation between states points to differences in regulation and in access to care.
Put plainly, the person who most often stands between a patient and the product is not a health professional. That is a structural feature of state programs, and it is one reason the federal and state pictures remain hard to reconcile.
What These Numbers Can and Cannot Tell You
Several limits apply to every figure in this article.
The counts cover only people who are formally registered. Anyone using cannabis for a health reason without a card, which is easy in a state with adult-use stores, is invisible here.
Not every state reports everything. In the 2022 round, 39 jurisdictions allowed medical cannabis, but only 34 reported patient numbers, 29 reported clinician numbers and 19 reported the conditions patients listed. California was left out of that analysis because its registry is voluntary; it had recorded just 113,862 patients cumulatively from 1996 through 2021.
The conditions are patient-reported qualifying conditions drawn from state paperwork. They are not diagnoses verified by the researchers, and a patient may qualify under one label while using cannabis mainly for another problem.
The design is descriptive. It shows what happened to enrollment; it cannot prove why, and it contains no information on doses, products or whether anyone got better.
Finally, the two new papers are research letters, a short format, and their detailed state tables were not available for this article. The 2024 national totals here are the publisher’s rounded figures.
Where Federal Law Stands After the Schedule III Move
The new letters arrive in a changed legal setting. Under a final order signed on April 22, 2026, and published in the Federal Register on April 28, two categories moved from Schedule I to Schedule III of the Controlled Substances Act: FDA-approved drug products containing marijuana, and marijuana covered by a state medical marijuana license. Everything else, including cannabis sold under state adult-use programs, stayed in Schedule I.
The order makes the medical registries described here more consequential, because the line between “medical” and “adult-use” cannabis now carries federal weight and not only state weight. It does not, however, turn a dispensary product into an approved medicine, and it does not by itself solve the evidence gap the researchers describe. We have covered separately why Schedule III leaves the main obstacles to cannabis research in place.
FAQ
About 3.9 million people were registered in state medical cannabis programs in 2024, according to the University of Michigan analysis published in Annals of Internal Medicine on September 29, 2026. That is up from about 747,000 in 2016. The figure counts registered patients only and is incomplete, because states report unevenly and some do not require registration.
More than 35,000 clinicians were authorized to approve patients for medical cannabis in 2024, up from about 29,500 in 2020. Not all of them are physicians: in the most recent detailed breakdown, for 2022, just over half held an MD or DO degree, and the rest were mainly nurse practitioners and physician assistants.
The most likely reason is the spread of adult-use legalization. In the team’s earlier data, 13 of 15 jurisdictions with adult-use laws lost medical patients between 2020 and 2022. The researchers suggest that people leave registries because they no longer need a card for legal access, because of fees and certification visits, or because they buy adult-use products for medical purposes.
Partly. Since April 2026, marijuana covered by a state medical marijuana license and FDA-approved products containing marijuana are classified in Schedule III, while all other marijuana, including state-legal adult-use cannabis, remains in Schedule I. Products sold in dispensaries are still not FDA-approved, so clinicians authorize access under state law and do not prescribe them. Rules on who qualifies, how to register and what a registration allows are set by each state and differ widely.
Legal Disclaimer
This article is for informational and educational purposes only. It summarizes published research and public records and does not constitute medical or legal advice. Cannabis laws in the United States differ from state to state and differ between state and federal level, and they change frequently. Nothing here should be read as a recommendation to use, buy, grow or possess cannabis, or as guidance on qualifying for a medical cannabis program. For decisions about your health, consult a licensed health professional; for questions about the law in your jurisdiction, consult a qualified attorney or the relevant state agency.
