Passengers in Tucson were treated to cookies and games at the gates, while employees got massages and barbecue, an airline spokeswoman said.
Southwest arrived in Tucson on May 23, 1994, with then-Chairman Herb Kelleher arriving aboard a specially painted jet dubbed “Arizona One.”
Southwest started Tucson service after purchasing Salt Lake City-based Morris Air, which flew from Tucson to Los Angeles, San Diego and Las Vegas.