UA 3911 then UA 2339 at Houston
Washington → Houston → Mc Allen
Timetable, Houston time
00:06UA 3911 from Washington at the gate
20:30UA 2339 to Mc Allen leaves the gate
20 h 24 apart on the timetable
UA 2339 leaves 20 h 24 after UA 3911 arrives on the timetable: more than half a day, so not a connection we count.