F9 4567 then UA 5802 at Denver
St Louis → Denver → Casper
Timetable, Denver time
21:30F9 4567 from St Louis at the gate
19:15UA 5802 to Casper leaves the gate
21 h 45 apart on the timetable, overnight
UA 5802 leaves 21 h 45 after F9 4567 arrives on the timetable: more than half a day, so not a connection we count.