UA 770 then CA 3174 at O'Hare
Barcelona → Chicago → Guangzhou
Timetable, Chicago time
18:00UA 770 from Barcelona at the gate
13:40CA 3174 to Guangzhou leaves the gate
19 h 40 apart on the timetable, overnight
CA 3174 leaves 19 h 40 after UA 770 arrives on the timetable: more than half a day, so not a connection we count.