AA 1799 then UA 3910 at O'Hare
Cancún → Chicago → Newark
Timetable, Chicago time
19:20AA 1799 from Cancún at the gate
07:30UA 3910 to Newark leaves the gate
12 h 10 apart on the timetable, overnight
UA 3910 leaves 12 h 10 after AA 1799 arrives on the timetable: more than half a day, so not a connection we count.