UA 474 then CA 3174 at O'Hare
Mexico City → Chicago → Guangzhou
Timetable, Chicago time
19:34UA 474 from Mexico City at the gate
13:40CA 3174 to Guangzhou leaves the gate
18 h 06 apart on the timetable, overnight
CA 3174 leaves 18 h 06 after UA 474 arrives on the timetable: more than half a day, so not a connection we count.