You’re right, air travel is what brought MLB to the west. I flew to the east coast in 56 on a TWA Super Constellation, it was a great flight except when we landed at La Guardia in a storm, we were bouncing around something terrible. lol
Having landed at,and taken off from,La Guardia a few times in my day I can assure that the bouncing around is SOP.It's part of the charm of the Big Apple.
However, what really expanded professional sports in the western USA was the arrival of the Boeing 707 and Douglas DC-8 on a large scale in the early 1960’s. That’s what made it possible for teams in San Francisco and Los Angeles to really flourish.