UA 3902 then UA 1977 at Houston
Toronto → Houston → Boston
Timetable, Houston time
08:27UA 3902 from Toronto at the gate
07:35UA 1977 to Boston leaves the gate
23 h 08 apart on the timetable, overnight
UA 1977 leaves 23 h 08 after UA 3902 arrives on the timetable: more than half a day, so not a connection we count.