Rules on alcohol and tobacco in the US are stricter than in many countries. Breaking them can lead to a fine, an arrest and problems with your visa.
You must be 21 or older to buy alcohol in every state.
You must be 21 or older to buy tobacco, cigarettes, e-cigarettes and vapes. This is federal law.
It does not matter if the legal age at home is 18. It does not matter that you are with your parents.
Buying alcohol for someone under 21 is a crime.
Stores, bars and restaurants ask for ID ("carding") even if you look older. Bring your passport or a US driver's license or state ID. Many places do not accept a foreign national ID card. They may refuse to serve you if they are unsure.
Where you can and cannot drink
Drinking in public (streets, parks, beaches, public transport) is illegal in most places. This differs by state and city.
Open container rules: in most states, an open bottle or can of alcohol in the passenger area of a car is illegal, even if the driver is not drinking. Keep it closed and in the trunk.
Where and when stores can sell alcohol differs by state. Some states sell beer and wine in supermarkets; others sell spirits only in state stores. Some places do not sell alcohol on Sunday mornings.
BYOB ("bring your own bottle") restaurants let you bring your own wine or beer. Ask first.
Smoking is banned inside most restaurants, bars, offices and public buildings, and often near doors and in parks.
Many apartment buildings are smoke-free. Read your lease.
Driving with a blood alcohol level of 0.08% or more is illegal in every state except Utah, where the limit is 0.05%. Many people reach 0.08% after just two or three drinks. For drivers under 21, almost any alcohol is illegal. A DUI (driving under the influence) can affect your visa (see the guide on DUI and your status). Use a taxi, rideshare or public transport.
Carrying an open drink from a party to the street.
Using a fake ID or someone else's ID. This is a crime.
Giving a beer to a 19-year-old friend at your home.