St. Louis Airport has only two terminals. Terminal 1 is used domestically, when Terminal 2, serves International purposes.
There are four concourses (A, B, C, and E) at the airport with four runways.
As was mentioned previously, Terminal 1 handles only domestic flights. It includes two concourses, which are A and C. The terminal itself consists of three different levels, where all of them serve different purposes and are divided into lower, mid and upper levels.
The lower level is used as an Arrival level. It includes such services as baggage claim, information points, banking facilities, and ground transportation options.
Mid-level is used solely for services and amenities. It provides such services as ATMs, USO Lounge, food, drink, and retail.
The upper level is the departure level and includes information points and food, drink, and retail concessions.
Terminal 1 is a home for two concourses that are divided into A and C.
Gates of concourse A are A2-A6, A8-A10, A12, A14-A19, and A21.
Gates of concourse C are C1, C3, C8, C10, C12, C15-C19, C21, C23, C27, and C28.
International flights and passengers are operated in Terminal 2, where the leading carrier is Southwest Airlines.
International Terminal consists of two different levels. The lower level serves as an arrival one and is available for immigration and customs, baggage claim, and ground transportation services. The upper level is used as a departure level and includes check-in desks, food, shops and drink and retail, concessions.
Gates of concourse E are: E2, E4, E6, E8, E10, E12, E14, E16, E18, E20, E22, E24, E25, E29, E31, E33.
Gates used by Southwest Airlines are E4, E6, E8, E10, E12, E14, E16, E18, E20, and E22.