The short answer
It depends on the state you are buying in. In a state that licenses recreational stores, you show a government-issued photo ID and buy without a card. Where the only licensed store is a medical one, you need whatever that state's program requires, which is usually a card. In the states that license no cannabis store at all, a card does not let you buy.
The detail
A medical cannabis card is one state's permission, issued to one person. You apply to your own state's program for it, and each program sets who may apply, what it costs and how long the card lasts. What a medical store asks to see, and how it checks it, is set by the state that licensed the store.
Federal law lists marijuana in schedule I of its drug schedules (21 U.S.C. § 812. Schedules of controlled substances). A final rule of April 28, 2026 moved two categories to schedule III, and one of them is marijuana subject to a state medical marijuana license, which is why a state's paper now carries federal weight (Schedules of Controlled Substances: Rescheduling of Food and Drug Administration Approved Products Containing Marijuana From Schedule I to Schedule III; Corresponding Change to Permit Requirements, 91 FR 22714 (Apr. 28, 2026)).
Possessing a controlled substance is a federal offense unless federal law authorizes it (21 U.S.C. § 844. Penalties for simple possession). The federal government runs no medical cannabis program and issues no card. Under the April 2026 rule a document your state accepts is enough for a store registered under that rule to dispense to you (Schedules of Controlled Substances: Rescheduling of Food and Drug Administration Approved Products Containing Marijuana From Schedule I to Schedule III; Corresponding Change to Permit Requirements, 91 FR 22714 (Apr. 28, 2026)). How do I get a medical cannabis card? sets out what that document has to carry. Read what federal law says about weed for what federal law does with a state's license.
In a state that licenses both kinds of store, a card can still change the minimum age and the amount you may buy, because a state sets those separately for its medical program.
What varies by state
Every state and the District of Columbia is in one of the groups below.
The 23 states that license a recreational store: Alaska, Arizona, California, Colorado, Connecticut, Delaware, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nevada, New Jersey, New Mexico, New York, Ohio, Oregon, Rhode Island, Vermont and Washington.
A medical store is the only kind licensed in 20 more states and districts: Alabama, Arkansas, District of Columbia, Florida, Georgia, Hawaii, Iowa, Kentucky, Louisiana, Mississippi, Nebraska, New Hampshire, North Dakota, Oklahoma, Pennsylvania, South Dakota, Texas, Utah, Virginia and West Virginia. Most of those programs issue a card. Texas enters a physician's prescription in a state registry instead, and a few states work from a practitioner's written recommendation rather than a card. Each state's page says which.
In another 5 states the only counter you can lawfully buy cannabis products from sells hemp-derived ones, and no cannabis store of either kind is licensed: Kansas, South Carolina, Tennessee, Wisconsin and Wyoming. Another 2 license no shop of any kind: Idaho and North Carolina. This site cannot say for Indiana, which publishes its Code in a form this site could not read.
Each state's page gives the rule and the statute behind it.
What to watch out for
Your card names you and the state that issued it. Another state decides for itself whether to accept a card from yours. This site records whether a state accepts a card from another state only where that state's own source says so, so read that state's medical section before you rely on your card there.
A shop selling hemp-derived products is not a licensed cannabis store, and it asks for no card. Every listing on this site says which kind of shop it is, and names the authority that licensed it.
A state changes group when its law authorizes a new kind of store. Its page carries the date its facts were last checked.
Where to go next
Cannabis law, state by state holds a page for every state and the District of Columbia, and one for federal law.
You can search the store directory by city or by ZIP code. Where this site holds records for a state, its legality page and its store list link to each other, so you can move between the rule and the stores it applies to.