Pacific Southwest Airlines began as an intrastate carrier on May 5, 1949. On December 15, 1978, after growing rapidly in California, it added its first interstate route and grew rapidly again in the Pacific Northwest, Southwest and Mexico. It was acquired by USAir on May 29, 1987 and the merger was completed on April 9, 1988 and the airline known as PSA, the airline with a smile, faded away.