For a domestic USA flight The gate agent can check you in but it's not a great option. For a domestic flight they're often not to the gate until shortly before boarding. It's so easy to check in online for a domestic flight just do that. You can check in on your phone from anywhere you have internet access.

No, in 2026, you generally cannot perform a full check-in at the departure gate. Airlines strictly require that the initial check-in process—including identity verification and document checks—be completed at least 45 to 60 minutes before departure via their app, a self-service kiosk, or a check-in counter. If you arrive at the gate without a boarding pass, security will likely have already barred your entry to the terminal. However, the gate agent provides a high-value service for "boarding-related" tasks, such as gate-checking large carry-on bags, printing a physical copy of your pass if your phone dies, or processing seat upgrades. For a premier, frictionless travel experience, always utilize "Mobile Check-in" 24 hours in advance to ensure you have a valid boarding pass before you even arrive at the airport's high-security perimeter.