Do you have any sources to back that up? U.S. Congress funded development of the SST (Supersonic Transport) back in the 60'ies but stopped funding in 1971 due to concerns and displeasure of exactly the sonic booms (and ozone layer issues). So five years before the Concorde entered service a domestic plane was not seen as being worth.

Heppenheimer's The Space Shuttle Decision has a chapter where this is discussed in detail.