AA 3989 then UA 3376 at O'Hare
Cedar Rapids → Chicago → St Louis
Timetable, Chicago time
19:49AA 3989 from Cedar Rapids at the gate
11:00UA 3376 to St Louis leaves the gate
15 h 11 apart on the timetable, overnight
UA 3376 leaves 15 h 11 after AA 3989 arrives on the timetable: more than half a day, so not a connection we count.