AA 9866 then AA 3970 at O'Hare
Marquette → Chicago → Wilmington
Timetable, Chicago time
10:30AA 9866 from Marquette at the gate
08:21AA 3970 to Wilmington leaves the gate
21 h 51 apart on the timetable, overnight
AA 3970 leaves 21 h 51 after AA 9866 arrives on the timetable: more than half a day, so not a connection we count.