WN 209 then DL 1623 at Denver
St Louis → Denver → Salt Lake City
Timetable, Denver time
18:50WN 209 from St Louis at the gate
18:00DL 1623 to Salt Lake City leaves the gate
23 h 10 apart on the timetable, overnight
DL 1623 leaves 23 h 10 after WN 209 arrives on the timetable: more than half a day, so not a connection we count.