UA 3913 then UA 6166 at Houston
Denver → Houston → Des Moines
Timetable, Houston time
21:22UA 3913 from Denver at the gate
11:59UA 6166 to Des Moines leaves the gate
14 h 37 apart on the timetable, overnight
UA 6166 leaves 14 h 37 after UA 3913 arrives on the timetable: more than half a day, so not a connection we count.