UA 3500 then CA 3174 at O'Hare
Toronto Pearson → Chicago → Guangzhou
Timetable, Chicago time
16:44UA 3500 from Toronto Pearson at the gate
13:40CA 3174 to Guangzhou leaves the gate
20 h 56 apart on the timetable, overnight
CA 3174 leaves 20 h 56 after UA 3500 arrives on the timetable: more than half a day, so not a connection we count.