The 77th Aero Service Squadron was organized at Rich Field, Texas on 20 February 1918 with 2Lt. George P. Southworth as the squadron's first commander. On 28 February the squadron along with the 78th and 79th Aero Squadrons (which had also been born at Rich Field) moved by train on the Missouri–Kansas–Texas Railroad (commonly known as the Katy Railway) to Taliaferro Field #1 (later named Hicks Field), Texas. The 77th would then move to Taliaferro Field # 2 (later named Barron Field), Texas on 18 March 1918. In May 1918 2Lt. John Mason Tilney became squadron commander. On 21 July 1918 the 77th was redesignated Squadron A, Barron Field, Texas. A letter dated 24 July 1918 states "The use of numerical designations of squadrons will be restricted to those overseas and the eighty reserve squadrons authorized to be established at all times in this country". The vacated numbers were to be assigned to new squadrons as they were organized to replace squadrons shipped overseas. Some time after the squadrons designation was changed 2Lt. Edward S. Winfree took command and finally 2Lt. Hugh C. Downey became the squadron's last commander.