UA 5192 then AA 6487 at O'Hare
Jacksonville → Chicago → St Louis
Timetable, Chicago time
17:30UA 5192 from Jacksonville at the gate
15:18AA 6487 to St Louis leaves the gate
21 h 48 apart on the timetable, overnight
AA 6487 leaves 21 h 48 after UA 5192 arrives on the timetable: more than half a day, so not a connection we count.