AA 3111 then UA 3376 at O'Hare
St Louis → Chicago → St Louis
Timetable, Chicago time
13:00AA 3111 from St Louis at the gate
11:00UA 3376 to St Louis leaves the gate
22 h apart on the timetable, overnight
UA 3376 leaves 22 h after AA 3111 arrives on the timetable: more than half a day, so not a connection we count.