F9 4567 then UA 624 at Denver
St Louis → Denver → Las Vegas
Timetable, Denver time
21:30F9 4567 from St Louis at the gate
20:50UA 624 to Las Vegas leaves the gate
23 h 20 apart on the timetable, overnight
UA 624 leaves 23 h 20 after F9 4567 arrives on the timetable: more than half a day, so not a connection we count.