If you are traveling with baggage, you must check in at least 45 minutes prior to departure on a domestic flight and 60 minutes prior to departure on an international flight. (This applies to most airports although there are exceptions.). Of course, I always advocate for you to arrive to the airport much earlier than this. For a domestic flight, I will try to arrive around two hours before departure and for an international flight I will try to arrive around three hours prior to departure. Click here to see U.S. airports with special minimum required times.