AA 3310 then UA 3376 at O'Hare
Phoenix → Chicago → St Louis
Timetable, Chicago time
14:43AA 3310 from Phoenix at the gate
11:00UA 3376 to St Louis leaves the gate
20 h 17 apart on the timetable, overnight
UA 3376 leaves 20 h 17 after AA 3310 arrives on the timetable: more than half a day, so not a connection we count.