AA 470 then UA 3907 at O'Hare
Philadelphia → Chicago → Washington
Timetable, Chicago time
17:33AA 470 from Philadelphia at the gate
12:00UA 3907 to Washington leaves the gate
18 h 27 apart on the timetable, overnight
UA 3907 leaves 18 h 27 after AA 470 arrives on the timetable: more than half a day, so not a connection we count.