You can check-in your checked luggage at the airport's ticket desk, curb side (domestic only) or at a kiosk that allows you to tag your bags. This is available up until 3 hours before departure. Those who are Business Select and Rapid Rewards members have the option to check in their luggage quicker using the Fly by Priority check-in lanes at selected airports.

https://www.flysair.com/southw....est-airlines-baggage