AA 9866 then AA 3584 at O'Hare
Marquette → Chicago → Springfield Branson National
Timetable, Chicago time
10:30AA 9866 from Marquette at the gate
08:15AA 3584 to Springfield Branson National leaves the gate
21 h 45 apart on the timetable, overnight
AA 3584 leaves 21 h 45 after AA 9866 arrives on the timetable: more than half a day, so not a connection we count.