AA 3585 then UA 2148 at O'Hare
Key West → Chicago → Denver
Timetable, Chicago time
21:30AA 3585 from Key West at the gate
21:00UA 2148 to Denver leaves the gate
23 h 30 apart on the timetable, overnight
UA 2148 leaves 23 h 30 after AA 3585 arrives on the timetable: more than half a day, so not a connection we count.