The National Aeronautics and Space Administration and its predecessor, the National Advisory Committee for Aeronautics (NACA), have participated since 1920 in efforts to develop the technology required for supersonic cruise flight. Preliminary work concentrated on developing rudimentary test facilities and methods that would permit the investigation of supersonic problems. This was accompanied by research for defining aircraft and propulsion concepts for flight at speeds greater than the speed of sound. These early investigations contributed to the development of the joint U.S. Air Force/Navy/Bell-XS-1 airplane that was piloted on the first successful supersonic flight by Air Force Capt. Charles E. "Chuck" Yeager in 1947. Between 1956 and 1971, a strong research effort supported the USF supersonic B-70 and commercial supersonic transport concepts. After neither of these programs resulted in a production aircraft because of technical and political problems, NASA was given the responsibility of establishing the technology base for a viable supersonic cruise airplane. This latter effort, known as the NASA Supersonic Cruise Research (SCR) program, was conducted from 1971 to 1981. The NASA Variable Cycle Engine (VCE) program, a propulsion offshoot of SCR, was conducted from 1976 to 1981. The SCR program was somewhat unusual for a NASA program involving in-house and contractor participation. Several of the manufacturers provided company manpower and dollars to augment NASA funding and personnel, even though there was no contractual requirement for them to do so. Dissemination of technical information was almost immediate to all participants because data dumps and separate status reports were mutually transferred openly and with high frequency, and because of the day-to-day contacts by the major civilian and military airframe and propulsion system manufacturers. The disciplinary research/systems integration approach of the SCR and VCE programs led to a large number of major advances in the technology needed for supersonic flight. This document provides a historic perspective of supersonic cruise technology, beginning with the early NACA supersonic research and including efforts during the B-70 and SST phase. It also records technological progress made in the NASA SCR and VCE programs.