How long before departure should you be at the train station?

Times vary from airport to airport, from air carrier to air carrier and even from day to day. A general guideline is 1 1/2 hours before departure for US domestic travel when checking bags. 2 hours before departure for International departures. For major holiday travel, add another 30 minutes, just to be sure. If you have no bags to check-in, most carriers now have some form of online check-in or airport based kiOSk (self service) check-in that might allow you shave some time off your check-in.