AA 4413 then UA 3376 at O'Hare
Memphis → Chicago → St Louis
Timetable, Chicago time
19:50AA 4413 from Memphis at the gate
11:00UA 3376 to St Louis leaves the gate
15 h 10 apart on the timetable, overnight
UA 3376 leaves 15 h 10 after AA 4413 arrives on the timetable: more than half a day, so not a connection we count.