UA 3902 then DL 2709 at Houston
Toronto → Houston → Atlanta
Timetable, Houston time
08:27UA 3902 from Toronto at the gate
08:05DL 2709 to Atlanta leaves the gate
23 h 38 apart on the timetable, overnight
DL 2709 leaves 23 h 38 after UA 3902 arrives on the timetable: more than half a day, so not a connection we count.