High bypass turbofans can be used for supersonic transport, as can even more sophisticated efficiency wins, like geared turbofans. SST was killed by noise regul

High bypass turbofans can be used for supersonic transport, as can even more sophisticated efficiency wins, like geared turbofans. SST was killed by noise regulations in North America, which in turn were largely protectionism that Boeing demanded because their own SST project was a failure. It's not a coincidence that somehow no other country in the world had problems being overflow by supersonic jets.