AA 4802 then UA 3907 at O'Hare
Harrisburg → Chicago → Washington
Timetable, Chicago time
16:35AA 4802 from Harrisburg at the gate
12:00UA 3907 to Washington leaves the gate
19 h 25 apart on the timetable, overnight
UA 3907 leaves 19 h 25 after AA 4802 arrives on the timetable: more than half a day, so not a connection we count.