I can't confirm if it is true or not but I heard this a while ago. Those that are familiar with the terminal layout in PHL or work there can confirm. The border of the city of Philadelphia is a line that runs right in between terminal A & B. If you work in terminals B,C,D,E and F you are working within the borders of the city of Philadelphia and get charged the city wage tax. If you work in terminal A or A West, that is technically Tinicum Township in Delaware County, PA and you do not pay the city wage tax... Maybe someone that works for AA in PHL can confirm as the are in terminal A.