The chart below shows the official number of medical marijuana patients holding identification cards in the states (and District of Columbia) with mandatory registration. For states with voluntary (CA, ME) or no registration (WA), the patient number is an estimate from the Marijuana Policy Project. We listed four states (MD, MN, NH, NY) that have legalized medical marijuana but have not yet opened their patient registration programs. Those states were not included in our calculations to determine the total and average number of medical marijuana users, nor was Massachusetts because its program opened too recently to have registration numbers compiled.
We recognize the possibility that not all medical marijuana users register for identification cards and not all of the people registered have valid medical uses for the marijuana.
State population numbers are estimates from the US Census Bureau's 2013 data. We referenced state websites and called and emailed state officials to update the medical marijuana patient numbers in Oct. 2014. See all sources below.
Our national estimate of 2,434,192 medical marijuana users may not be nor is it intended to be scientifically or statistically sound. It is presented only to give a general reference point for discussion of medical marijuana use in the United States.6
How Many Legal Medical Marijuana Patients Are There in the United States?
Legal Medical Marijuana Patients: total medical marijuana users in 19 (out of 23) states and DC with legal medical marijuana (as of Oct. 2014)
Estimated number of users if medical marijuana were legal throughout all 50 US states and DC (based on avg. of 7.7 patients per 1,000)5
Notes: 1. California has 76,431 registered card holders, but registration is voluntary. The Marijuana Policy Project (MPP) estimated the number of California patients based on Oregon's patients per capita. Maine also has voluntary registration (1,480 registered card holders), so the estimate from MPP is based on Michigan's patient numbers. Washington did not have a registration program at the time this resource was created, so we used MPP's estimate of Washington patients based on Oregon's patients per capita. On Apr. 24, 2015, Washington Gov. Jay Inslee signed a bill to create a voluntary registry.
2. Illinois' application process opened on Sep. 2, 2014. By Friday, Sep. 5, more than 2,000 had people begun the application process to register for a medical cannabis identification card through the Illinois Department of Public Health. This number will likely continue to grow.
3. Maryland, Minnesota, New Hampshire, and New York have not yet opened patient registration as the program rules are still being determined (as of Oct. 27, 2014).
4. Massachusetts' registration system opened on Oct. 8, 2014, and the registration numbers are not yet available.
5. If the average number of medical marijuana patients per 1,000 residents in states with legal medical marijuana is extrapolated to all 50 states (population 316,128,839 as of 2013, according to the US Census Bureau), then the total number of medical marijuana users as of Oct. 27, 2014 would theoretically be 2,434,192 [7.7/1,000 x 316,128,839 = 2,434,192].
6. Jeff Dang, PhD, Director of Statistics and Quality Analysis at FAIR Health Inc., commented on our methodology in a Mar. 10, 2009 email to ProCon.org. Although Mr. Dang's statement is based on our 2009 patient estimate of 577,712, the method we used in 2014 to estimate patients is the same.
"ProCon.org should be congratulated for providing an estimate of the number of people who hold identification cards for medical marijuana in several states throughout the country. Furthermore, ProCon.org has provided an estimate that currently serves as a general reference point for enumerating the total number of medical marijuana patients in the country. ProCon.org has conscientiously disclosed many of the problems associated with their estimates and provided the algorithms that were used to derive the estimates (see [above] footnotes). However, two notable limitations should be added and have been delineated below.
First, the current estimate of 577,712 included data from a variety of sources (e.g. estimates from the Marijuana Policy Project and data from the Census Bureau). In several states, different data collection and estimation methods were employed. It is important to note that each approach contributes additional sources of bias and error that have not been teased apart or accounted for in the current estimate. More generally, the quality of the data have not been verified or described in detail. Secondly, it is clear that systematic probability sampling techniques were not employed therefore these numbers cannot be generalized to the rest of the nation. In other words, these particular states are not representative of all states in the US and the sample data are not representative of US population.
To derive more accurate estimates, rigorous research methods should be employed. In particular, random sampling remains the gold standard for estimating prevalence. The reality, however, is that research is often conducted on a shoestring budget and practical concerns often prevent the kind of research that is actually desired."
Alaska: Email from Medical Marijuana Program to ProCon.org, Sep. 12, 2014
California: "California Department of Public Health Medical Marijuana Program (MMP) Facts and Figures," cdph.ca.gov, Sep. 9, 2014 (registered); "Medical Marijuana Patient Numbers," mpp.org (accessed Oct. 27, 2014) (estimate)
Colorado: "Medical Marijuana Registry Program Update," colorado.gov, July 31, 2014