UA 367 then UA 1145 at San Francisco
Washington → San Francisco → Cancún
Timetable, San Francisco time
01:29UA 367 from Washington at the gatealso LH 7530, VA 8388, NZ 9181
23:00UA 1145 to Cancún leaves the gate
21 h 31 apart on the timetable
UA 1145 leaves 21 h 31 after UA 367 arrives on the timetable: more than half a day, so not a connection we count.