UA 3487 then AA 3484 at O'Hare
Columbus (Ohio) → Chicago → St Louis
Timetable, Chicago time
09:45UA 3487 from Columbus (Ohio) at the gate
09:30AA 3484 to St Louis leaves the gate
23 h 45 apart on the timetable, overnight
AA 3484 leaves 23 h 45 after UA 3487 arrives on the timetable: more than half a day, so not a connection we count.