How do you address an envelope to a person in army basic training?

Answer 1

Name

Unit

Location, State Zip Code

For location, it would be used the same way as the name of the city would be used. If they're at Fort Benning, for example, then Fort Benning would be used as the city.

As for the unit, you would need to put the company and battalion they're in. If they were in, for example, Charlie Company, 2nd Battalion, 58th Infantry, it would appear as "C 2/58" or "C 2/58 IN".

Army posts (and other military installations) are assigned ZIP codes, the same way any US city is.