They didn't have environmental concerns like they do today, during the 1960's and 1970's. For awhile, they were worried the world would freeze-over!

         SST concepts are there, but as NASA states, the only way to make them viable, which includes over-continental flying rather than over-water, the sonic boom must be either done away completely, or quiter than a baseball bat hitting a fastball. The sonic booms done over Oklahoma City proved that long-term sonic booms over a city cause complaints, and airliners flying over large cities daily (with a boom equal to that of any fighter jet or Concorde) would surely entail complaints. NASA's concepts for technology that would enable an SST to produce a negligable sonic boom outline an airliner with capacity of 50-85, which is no greater than a Bombardier CRJ700. The Concorde didn't hold many passengers either, 92-120 passengers. However, the problem is gettign it effecient. The inherint design is effecient, per-say, but to get the massive gain that widebodies got over narrowbodies, was range and capacity. If a supersonic airliner were to only hold 80 passengers, it would have to be both incredibly effecient, and fly very far. Ticket prices would be astronomical, and it wouldn't make much sense business-wise. I can see business jets like the Aerion SBJ possibly taking wealthy people and weel-to-do businesses to far places supersonic, but that still is stretching it.