AA 3484 then UA 3376 at O'Hare
St Louis → Chicago → St Louis
Timetable, Chicago time
19:05AA 3484 from St Louis at the gate
11:00UA 3376 to St Louis leaves the gate
15 h 55 apart on the timetable, overnight
UA 3376 leaves 15 h 55 after AA 3484 arrives on the timetable: more than half a day, so not a connection we count.