The T-37 was developed in response to the launch of the "Trainer Experimental (TX)" program for the United States Air Force (USAF) in early 1952. On 12 October 1954, the prototype XT-37 performed its maiden flight. While the first prototype was lost during spin tests, features to improve handling were installed upon subsequent prototypes, such as nose-mounted strakes and a heavily redesigned large tail unit, after which the USAF chose to order the aircraft into production as the T-37A. The service received the first production aircraft during June 1956.In response to the T-37A being underpowered, the USAF ordered an improved version, the T-37B, that was powered by uprated J-69-T-25 engines and was also equipped with improved avionics. A total of 552 new-built T-37Bs were constructed through 1973; all surviving T-37As were eventually upgraded to the T-37B standard as well. The T-37 served as the USAF's primary pilot training vehicle for over 50 years after its first flight. After completing initial training in the T-37, students progressed on to other advanced Air Force, Navy, Marine Corps or Allied trainers. A total of 1,269 T-37s were constructed prior to production ending in 1975. In 2009, the USAF withdrew its final T-37, having replaced the type with the newer turboprop-powered Beechcraft T-6 Texan II.In addition to its use as a trainer, an armed T-37C variant was developed as a weapons trainer. A dedicated attack variant, the A-37 Dragonfly, was also developed by Cessna during the 1960s in response to a need for counter-insurgency aircraft (COIN) aircraft for the Vietnam War. Both the A-37 and T-37C were exported to various other countries, leading to their adoption by the air forces of several South American nations.