AA 1603 then AA 3160 at Boston
Philadelphia → Boston → Chicago O'Hare
Timetable, Boston time
14:35AA 1603 from Philadelphia at the gate
18:16AA 3160 to Chicago O'Hare leaves the gate
3 h 41 apart on the timetable
The last days
AA 1603 and AA 3160 weren’t both flown 15 min to 12 h apart in the last 21 days.
Statistics from past flights, not live flight information. Always check times and your connection with your airline, and don’t base travel or booking decisions on these numbers.