 Pacific Seaboard would later move its entire operation to the eastern U.S., be renamed Chicago and Southern Air Lines, and in 1953 be acquired by and merged into Delta Air Lines.After the county's acquisition of the airfield, the County of San Luis Obispo extended runway 01/19 from to ; installed high intensity lights; and built a large hangar, ten T-Hangars and a terminal building between 1949 and 1952.In 1956 flights by Southwest Airways commenced with Martin 4-0-4s.