UA 6144 then DL 2709 at Houston
Monterrey → Houston → Atlanta
Timetable, Houston time
10:20UA 6144 from Monterrey at the gate
08:05DL 2709 to Atlanta leaves the gate
21 h 45 apart on the timetable, overnight
DL 2709 leaves 21 h 45 after UA 6144 arrives on the timetable: more than half a day, so not a connection we count.