AA 3178 then UA 3376 at O'Hare
Charlotte → Chicago → St Louis
Timetable, Chicago time
17:40AA 3178 from Charlotte at the gate
11:00UA 3376 to St Louis leaves the gate
17 h 20 apart on the timetable, overnight
UA 3376 leaves 17 h 20 after AA 3178 arrives on the timetable: more than half a day, so not a connection we count.