UA 351 then AA 3484 at O'Hare
Washington National → Chicago → St Louis
Timetable, Chicago time
10:50UA 351 from Washington National at the gate
09:30AA 3484 to St Louis leaves the gate
22 h 40 apart on the timetable, overnight
AA 3484 leaves 22 h 40 after UA 351 arrives on the timetable: more than half a day, so not a connection we count.