UA 2737 then CA 3174 at O'Hare
Cancún → Chicago → Guangzhou
Timetable, Chicago time
17:59UA 2737 from Cancún at the gate
17:25CA 3174 to Guangzhou leaves the gate
23 h 26 apart on the timetable, overnight
CA 3174 leaves 23 h 26 after UA 2737 arrives on the timetable: more than half a day, so not a connection we count.