AA 3062 then UA 3876 at O'Hare
Las Vegas → Chicago → Miami
Timetable, Chicago time
05:59AA 3062 from Las Vegas at the gate
21:00UA 3876 to Miami leaves the gate
15 h 01 apart on the timetable
UA 3876 leaves 15 h 01 after AA 3062 arrives on the timetable: more than half a day, so not a connection we count.