DL 3968 then AS 421 at Seattle
Vancouver → Seattle → Denver
Timetable, Seattle time
16:53DL 3968 from Vancouver at the gate
13:59AS 421 to Denver leaves the gate
21 h 06 apart on the timetable, overnight
AS 421 leaves 21 h 06 after DL 3968 arrives on the timetable: more than half a day, so not a connection we count.