The development took place in the 1960s as part of a government-funded design competition to build an American SST[1] as the joint Anglo-French Concorde and the short-serviced Soviet Tupolev Tu-144 were underway.

The design, however, due to being slower and smaller than the expectations of the American SST Race, was rejected in favor of the Lockheed and Boeing designs, allowing them to get further study.

In some respects, the NAC-60 was a scaled-up variant of North American's bomber prototype, the XB-70 Valkyrie.

The use of high-lift devices on the leading edge of the wing lowered the landing angles to the point where the "drooping nose" was not required, and a more conventional rounded design was used.

Compared to the other designs, the rounded nose profile and more cylindrical cross-section gave the NAC-60 a decidedly more conventional look than the other entries.