AA 4504 then UA 4791 at O'Hare
South Bend → Chicago → South Bend
Timetable, Chicago time
18:35AA 4504 from South Bend at the gate
10:25UA 4791 to South Bend leaves the gate
15 h 50 apart on the timetable, overnight
UA 4791 leaves 15 h 50 after AA 4504 arrives on the timetable: more than half a day, so not a connection we count.