UA 3902 then UA 2616 at Houston
Toronto → Houston → Chicago
Timetable, Houston time
08:27UA 3902 from Toronto at the gate
06:20UA 2616 to Chicago leaves the gate
21 h 53 apart on the timetable, overnight
UA 2616 leaves 21 h 53 after UA 3902 arrives on the timetable: more than half a day, so not a connection we count.