LA 6139 then UA 412 at San Francisco
Boston → San Francisco → Mexico City
Timetable, San Francisco time
23:58LA 6139 from Boston at the gate
22:48UA 412 to Mexico City leaves the gatealso AC 5025
22 h 50 apart on the timetable, overnight
UA 412 leaves 22 h 50 after LA 6139 arrives on the timetable: more than half a day, so not a connection we count.