UA 4397 then AA 3484 at O'Hare
Columbia Metropolitan → Chicago → St Louis
Timetable, Chicago time
11:59UA 4397 from Columbia Metropolitan at the gate
09:30AA 3484 to St Louis leaves the gate
21 h 31 apart on the timetable, overnight
AA 3484 leaves 21 h 31 after UA 4397 arrives on the timetable: more than half a day, so not a connection we count.