The sonic boom limited them to only flying over the sea. They could technically fly at any airport that handles large passenger jets. But if you fly supersonic over land you will piss off everyone below you.
The outcomes were SUBSTANTIALLY worse than the US government expected. The results of this study are why even war planes rarely go supersonic over the continental US.
I remember the sonic boom over the Seattle area in the summer of 2010 when Obama was in town. A seaplane accidentally violated the 10 mile exclusion zone around Air Force 1 at Boeing Field and two F-15s were scrambled from Portland International Airport (Oregon National Guard operates the fighters tasked with protection from Northern California to the Canadian border). It was quite exciting.