Different ways in which you can check in on American Airlines are:
Online: Online check in is available starting 24 hours before scheduled departure and continues till 45 or 90 minutes prior to departure for domestic or international flights respectively.
Mobile: Mobile check-in is also possible and in some cities, AA also provides the boarding passes on your mobile.
Self-service Kiosk: You can make use of the self-service kiosks present at the airport for getting your boarding pass. Bags can also be checked in here.
Ticket counter check in
Flagship check in: This is designed to expedite your passage through security checks and provides you a personal representative who assists you all the way.
Suggested Arrival Times at Airport for American Airlines Flights
a) Within USA + flights to Puerto Rico, US Virgin Islands and Hawaii, at least 60 minutes prior to departure if not checking in bags. Otherwise, 90 minutes.
b) Flights departing Hawaii and US Virgin Islands, you are expected to arrive at airport at least 2 hours before departure (Honolulu 2.5 hours)
c) Flights to international destinations: At a minimum 2 hours before departure.
Minimum Times for checking in of passengers and baggage
a) For flights between US, Puerto Rico and US Virgin Islands, check in cutoff time is 45 for most of the cities. However, it can also be a minimum of 30 minutes for some of the cities. You are also required to be at the gate and ready for boarding at least 30 minutes prior to scheduled departure.
Bags have to be checked in at least 30 minutes prior to scheduled departure of flights.
b) For flights starting from US cities for international destinations or those originating from airports outside the country, minimum check-in time is of 60 minutes (exceptions also exist). You are required to be at the gate and ready for boarding at least 30 minutes before scheduled departure.
Bags are checked in at least 30 minutes before departure.