AA 2903 then DL 2804 at Boston
Philadelphia → Boston → Chicago O'Hare
Timetable, Boston time
08:40AA 2903 from Philadelphia at the gate
20:55DL 2804 to Chicago O'Hare leaves the gate
12 h 15 apart on the timetable
DL 2804 leaves 12 h 15 after AA 2903 arrives on the timetable: more than half a day, so not a connection we count.