UA 3905 then DL 1585 at Houston
Cancún → Houston → Atlanta
Timetable, Houston time
13:29UA 3905 from Cancún at the gate
10:00DL 1585 to Atlanta leaves the gate
20 h 31 apart on the timetable, overnight
DL 1585 leaves 20 h 31 after UA 3905 arrives on the timetable: more than half a day, so not a connection we count.