AA 9866 then UA 4783 at O'Hare
Marquette → Chicago → Rapid City
Timetable, Chicago time
10:30AA 9866 from Marquette at the gate
08:40UA 4783 to Rapid City leaves the gate
22 h 10 apart on the timetable, overnight
UA 4783 leaves 22 h 10 after AA 9866 arrives on the timetable: more than half a day, so not a connection we count.