Southwest Airlines uses Terminal 1 at Harry Reid International Airport (LAS) in Las Vegas for both domestic and international flights. This includes arrivals and departures.

Within Terminal 1, Southwest utilizes gates in concourses B and C. So, when navigating the airport, keep an eye out for those areas.

Here are some additional details you might find helpful:

• Terminal 1 also houses other airlines like Delta, Allegiant, Avelo, and Spirit.
• If you have access to a lounge through a credit card (like Priority Pass or Centurion Lounge), be aware that they are located in different concourses than Southwest's gates. Plan extra time if you want to check them out.
• Harry Reid International Airport offers various amenities like free Wi-Fi, shops, restaurants, and even slot machines!

I hope this clarifies which terminal Southwest uses in Las Vegas. Have a fantastic trip!