UA 1593 then UA 3237 at Houston
San Francisco → Houston → Mc Allen
Timetable, Houston time
05:12UA 1593 from San Francisco at the gate
19:45UA 3237 to Mc Allen leaves the gate
14 h 33 apart on the timetable
UA 3237 leaves 14 h 33 after UA 1593 arrives on the timetable: more than half a day, so not a connection we count.