AA 1894 then UA 3876 at O'Hare
Dallas-Fort Worth → Chicago → Miami
Timetable, Chicago time
23:59AA 1894 from Dallas-Fort Worth at the gate
21:00UA 3876 to Miami leaves the gate
21 h 01 apart on the timetable, overnight
UA 3876 leaves 21 h 01 after AA 1894 arrives on the timetable: more than half a day, so not a connection we count.