The Deregulation Act of 1978 included a provision that the CAB be disbanded. That actually occurred on January 1 of 1980 or 81 (I believe).
Airlines can go wherever they want to, as long as airports have facilities to lease them.
Tom in NO (at MSY)
P.S. You could devote a lot of space on this forum to the effects of deregulation on the US airline Industry. If you ask me, it's what put BN, NA, OZ, PS, OC, etc out of business.
"The criminal ineptitude makes you furious"-Bruce Springsteen, after seeing firsthand the damage from Hurricane Katrina