Def, your boarding bass..also, the attendants @ the Ticket counter will let you know right before they send you to TSA.. True, sometimes they tend to change them..but they'll most likely announce the change as well. If in doubt, always look for a worker/attendant in any Gate. They'll also be able to assist you.
Boarding pass. I recommend checking the Arrival & Departure screens for updates. I've had flights change from Terminal A to Terminal C while on layover in
It is on your boarding pass.
O boarding pass
There are maps all around the airport that indicate the different terminals
If you are departing on American you can check in at any Terminal because they have counters at all Terminals. For all others read the signs as you enter and it will tell you where to go. If you are connecting, check your boarding pass for the information or your carrier.
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