AA 4504 then UA 3534 at O'Hare
South Bend → Chicago → Louisville
Timetable, Chicago time
18:35AA 4504 from South Bend at the gate
14:30UA 3534 to Louisville leaves the gate
19 h 55 apart on the timetable, overnight
UA 3534 leaves 19 h 55 after AA 4504 arrives on the timetable: more than half a day, so not a connection we count.