UA 3878 then AM 419 at Houston
IAB → Houston → Mexico City
Timetable, Houston time
22:40UA 3878 from IAB at the gate
11:19AM 419 to Mexico City leaves the gate
12 h 39 apart on the timetable, overnight
AM 419 leaves 12 h 39 after UA 3878 arrives on the timetable: more than half a day, so not a connection we count.