UA 3672 then AA 3484 at O'Hare
Richmond → Chicago → St Louis
Timetable, Chicago time
12:00UA 3672 from Richmond at the gate
09:30AA 3484 to St Louis leaves the gate
21 h 30 apart on the timetable, overnight
AA 3484 leaves 21 h 30 after UA 3672 arrives on the timetable: more than half a day, so not a connection we count.