AA 3428 then UA 3376 at O'Hare
Pensacola → Chicago → St Louis
Timetable, Chicago time
14:44AA 3428 from Pensacola at the gate
11:00UA 3376 to St Louis leaves the gate
20 h 16 apart on the timetable, overnight
UA 3376 leaves 20 h 16 after AA 3428 arrives on the timetable: more than half a day, so not a connection we count.