AA 4504 then UA 5548 at O'Hare
South Bend → Chicago → Nashville
Timetable, Chicago time
18:35AA 4504 from South Bend at the gate
15:49UA 5548 to Nashville leaves the gate
21 h 14 apart on the timetable, overnight
UA 5548 leaves 21 h 14 after AA 4504 arrives on the timetable: more than half a day, so not a connection we count.