AA 4189 then UA 3376 at O'Hare
Missoula → Chicago → St Louis
Timetable, Chicago time
17:52AA 4189 from Missoula at the gate
11:00UA 3376 to St Louis leaves the gate
17 h 08 apart on the timetable, overnight
UA 3376 leaves 17 h 08 after AA 4189 arrives on the timetable: more than half a day, so not a connection we count.