Xi'an Xiguan Airport, also known as Hsian Airfield during World War II, was built in 1924 under the directives of Zhang Xueliang of the Fengtian Army. Military usage began with the Nationalist Chinese Air Force, specifically the 6th Reconnaissance-Attack/Scout-Attack Group, which was stationed there in 1929–30 and deployed during the Central Plains War. During the War of Resistance-World War II (1942–1945), the airport was utilized by the United States Army Air Forces Fourteenth Air Force as part of the China Defensive Campaign. The American forces primarily used the airfield for photo-reconnaissance with unarmed P-38 Lightnings, and also stationed P-61 Black Widow night interceptor aircraft, P-47 Thunderbolts day fighters, and C-47 Skytrain transports for supplies. The American facilities at the airport were closed in September 1945. The airport served as Xi'an's main airport until its closure on September 1, 1991, when it was replaced by Xi'an Xianyang International Airport. The site was subsequently converted into a civil park.