AA 9866 then UA 359 at O'Hare
Marquette → Chicago → Mexico City
Timetable, Chicago time
10:30AA 9866 from Marquette at the gate
08:55UA 359 to Mexico City leaves the gate
22 h 25 apart on the timetable, overnight
UA 359 leaves 22 h 25 after AA 9866 arrives on the timetable: more than half a day, so not a connection we count.