The USAF Strategic Air Command had C-119 Flying Boxcars in service from 1955 - 1973.

The C-119s saw service with the 456th Troop Carrier Wing which was attached to the Strategic Air Command from 25 April 1955 to 26 May 1956. The C-119s performed aerial recovery of high altitude balloon-borne instrument packages. C-119s also performed several aerial recoveries of film-return capsules during the early years of the Corona spy satellite program.

The C-119 would go on to see extensive service in Vietnam, beginning in 1954 with aircraft secretly loaned by the CIA to French forces for troop support. These aircraft were generally flown in French markings by American CIA pilots often accompanied by French officers and support staff. The C-119 was to play a major role during the siege at Dien Bien Phu, where they flew into increasingly heavy fire while dropping supplies to the besieged French forces.

After its retirement from active duty, many C-119s and R4Q's soldiered on in the US Navy, Air Force Reserve and Air National Guard until the mid-1970s, and until recently they were still in use by the Taiwanese Air Force. The last military use of the C-119 by the United States ended in 1974 when a single squadron of Navy R4Qs based at Selfridge ANG Base near Detroit, Michigan, and two squadrons based at Naval Air Station Long Beach, California replaced their R4Qs with newer aircraft.