UA 4740 then AA 3484 at O'Hare
Milwaukee → Chicago → St Louis
Timetable, Chicago time
13:15UA 4740 from Milwaukee at the gate
09:30AA 3484 to St Louis leaves the gate
20 h 15 apart on the timetable, overnight
AA 3484 leaves 20 h 15 after UA 4740 arrives on the timetable: more than half a day, so not a connection we count.