AA 9866 then AA 1672 at O'Hare
Marquette → Chicago → Harrisburg
Timetable, Chicago time
10:30AA 9866 from Marquette at the gate
08:20AA 1672 to Harrisburg leaves the gate
21 h 50 apart on the timetable, overnight
AA 1672 leaves 21 h 50 after AA 9866 arrives on the timetable: more than half a day, so not a connection we count.