AA 4504 then UA 3683 at O'Hare
South Bend → Chicago → Buffalo
Timetable, Chicago time
18:35AA 4504 from South Bend at the gate
14:17UA 3683 to Buffalo leaves the gate
19 h 42 apart on the timetable, overnight
UA 3683 leaves 19 h 42 after AA 4504 arrives on the timetable: more than half a day, so not a connection we count.