AA 3822 then UA 3376 at O'Hare
Harrisburg → Chicago → St Louis
Timetable, Chicago time
16:38AA 3822 from Harrisburg at the gate
11:00UA 3376 to St Louis leaves the gate
18 h 22 apart on the timetable, overnight
UA 3376 leaves 18 h 22 after AA 3822 arrives on the timetable: more than half a day, so not a connection we count.