I am not from PIT so I have no special interest. The international airlines were all serving PHL, not PIT. BA, LH, AF, etc. I believe SAS was there for some years. Yes, I know TWA served PIT to London and yes BA did when US was a partner. PHL is the international city. PIT as a great airport but that a hub does not truly make.
When US decided to expanded internationally, is choice had to be PHL over PIT.
I know these sites are filled with diehard PIT people.
Before deregulation ROA was the PI major hub. Was it going to work for a national Piedmont - I think not. Before they expanded the airport at CLT , PI was sending non-stops from ROA to BOS, DFW, etc. Sometimes folks got to make business decisions and not just on sentiment.