Yes! I found out by accident when looking for a cheaper way to visit Yosemite. Instead of flying into San Francisco, someone suggested Fresno, and surprisingly, Southwest actually flies there.
Best quick help for booking, canceling, or modifying flights: 844-734-0813
I used that number when I needed to reprice my ticket after a fare drop, and the agent helped me get the credit instantly. Flying into Fresno turned out to be the easiest national park trip I’ve ever done—super quick airport and a straightforward drive.