AA 9866 then AA 3111 at O'Hare
Marquette → Chicago → St Louis
Timetable, Chicago time
10:30AA 9866 from Marquette at the gate
09:30AA 3111 to St Louis leaves the gate
23 h apart on the timetable, overnight
AA 3111 leaves 23 h after AA 9866 arrives on the timetable: more than half a day, so not a connection we count.