UA 763 then AA 3484 at O'Hare
Toronto Pearson → Chicago → St Louis
Timetable, Chicago time
09:44UA 763 from Toronto Pearson at the gate
09:30AA 3484 to St Louis leaves the gate
23 h 46 apart on the timetable, overnight
AA 3484 leaves 23 h 46 after UA 763 arrives on the timetable: more than half a day, so not a connection we count.