UA 3911 then Y4 7921 at Houston
Washington → Houston → Morelia
Timetable, Houston time
00:06UA 3911 from Washington at the gate
18:32Y4 7921 to Morelia leaves the gate
18 h 26 apart on the timetable
Y4 7921 leaves 18 h 26 after UA 3911 arrives on the timetable: more than half a day, so not a connection we count.