That outbreak happened in Philly. It was also around the same time (1968) that the horrible abuses at Pennhurst Asylum (for the feeble-minded and epileptic) were uncovered by ABC’s local affiliate reporter Bill Baldini. Still took them another 15 years to close the place. Now it’s a haunted attraction.
Legionnaires was named because of the 1976 American Legion convention in Philly, where there were so many who fell ill. I will agree that it may have been looked into before that. You are probably privy to info I’m not aware of, so I will defer to you. I was just coming of age then, and I remember hearing about Legionnaires at that time.