UA 3913 then UA 787 at Houston
Denver → Houston → Chicago
Timetable, Houston time
21:22UA 3913 from Denver at the gate
13:40UA 787 to Chicago leaves the gate
16 h 18 apart on the timetable, overnight
UA 787 leaves 16 h 18 after UA 3913 arrives on the timetable: more than half a day, so not a connection we count.