AA 642 then UA 3487 at O'Hare
Dallas-Fort Worth → Chicago → Key West
Timetable, Chicago time
13:10AA 642 from Dallas-Fort Worth at the gate
11:00UA 3487 to Key West leaves the gate
21 h 50 apart on the timetable, overnight
UA 3487 leaves 21 h 50 after AA 642 arrives on the timetable: more than half a day, so not a connection we count.