UA 640 then DL 3876 at Denver
Vancouver → Denver → Austin
Timetable, Denver time
12:20UA 640 from Vancouver at the gate
09:42DL 3876 to Austin leaves the gate
21 h 22 apart on the timetable, overnight
DL 3876 leaves 21 h 22 after UA 640 arrives on the timetable: more than half a day, so not a connection we count.