TWA began service in the Pacific in 1969. The Round the World service began Oct-1971. But, many "route standardization" agreements between airlines were made during the 1970's, with permission and approval by the CAB. One of these agreements was between Pan Am and TWA.
An agreement reached in Oct-1974 called for TWA to suspend its routes across the Pacific and east to Saudi Arabia, including Honolulu, Guam, Taipei, Okinawa, Hong Kong, Bangkok, Bombay, routes to Germany, and the LHR-IAD route; in turn Pan Am would suspend routes to France, Austria, Portugal, Spain, Morocco, LHR-ORD/LAX/PHI (though PA kept the MIA-SJU-LIS-MAD-FCO route). The routes were cut Feb/Mar-1975.