Traveling inside the US is usually simple. Leaving the US and coming back needs more planning, and the rules depend on your status.
At airport security (TSA), adults show an accepted ID. A foreign passport is accepted. A green card and a work permit (EAD) are accepted too.
A US driver's license or state ID must be REAL ID-compliant (marked with a star) to be used for flying. Travelers without an accepted ID may be sent to a slower identity check, which costs $45.
Even on domestic trips, adults must carry proof of immigration registration (such as your I-94 or green card). Some routes, especially near the borders, have immigration checkpoints on roads and at some airports.
Students and workers: tell your school or employer if you will be away for a long time.
Your driver's license is valid in all states. If you move to another state, you usually must get a new license there within a set time. This differs by state.
Check these before you book:
Passport: valid for your whole trip, and many countries require 6 months' validity.
US visa stamp: if it has expired, you will need a new one abroad before returning (except some short trips to Canada and Mexico under special rules). Appointment waits can be long.
F-1 / J-1: a recent travel signature on your I-20 or DS-2019 from your school.
H-1B, L-1, O-1 and dependents: your latest I-797 approval and, often, recent pay stubs and an employer letter.
Pending green card application: do not leave without advance parole, or the application may be treated as abandoned (some H and L holders are exceptions).
Green card holders: trips longer than 6 months can bring questions; one year or longer usually needs a reentry permit obtained before leaving.
Refugees and asylees: travel with a refugee travel document, and never to the country you fled without a lawyer's advice.
Entry rules for your destination, including transit visas.
See the guides for your status for details.
Answer CBP's questions truthfully and carry the documents above in your carry-on bag.
Declare food and money as required (see the customs guide).
After you arrive, check your new I-94 online at i94.cbp.dhs.gov.
Flying abroad with a pending green card application and no advance parole.
Assuming an expired visa stamp does not matter for return.
Packing documents in checked luggage.