UA 3915 then AA 4480 at O'Hare
Miami → Chicago → Louisville
Timetable, Chicago time
22:25UA 3915 from Miami at the gate
19:00AA 4480 to Louisville leaves the gate
20 h 35 apart on the timetable, overnight
AA 4480 leaves 20 h 35 after UA 3915 arrives on the timetable: more than half a day, so not a connection we count.