WN 209 then UA 549 at Denver
St Louis → Denver → Des Moines
Timetable, Denver time
18:50WN 209 from St Louis at the gate
17:48UA 549 to Des Moines leaves the gate
22 h 58 apart on the timetable, overnight
UA 549 leaves 22 h 58 after WN 209 arrives on the timetable: more than half a day, so not a connection we count.