In order to bartend in the United States you must be either 18 or 21 years of age.
Which states are 18 and which are 21?

Hi there,

Actually, there are varying requirements in each state which
differentiate between servers and bartenders.

In Ohio, for instance, one may serve alcohol (as a waitress) at the
age of 19, but must be 21 to pour (tend bar).  To be allowed to handle
packaged alcohol (ring out beer, etc. at the grocery store) one must
be 18.

To get state by state information, you need to contact each of the 50
State Liquor Control boards.  There is no centralized listing of these
regulations, as they are handled at the state level and change often. 
Most states (to my knowledge) require that one be 21 to pour.

--Missy

Hi,

Here are the links for all the state Alcohol laws.
http://www.restaurant.org/legal/state_agencies.cfm

Lisaradha