AA 4504 then UA 5637 at O'Hare
South Bend → Chicago → Milwaukee
Timetable, Chicago time
18:35AA 4504 from South Bend at the gate
16:00UA 5637 to Milwaukee leaves the gate
21 h 25 apart on the timetable, overnight
UA 5637 leaves 21 h 25 after AA 4504 arrives on the timetable: more than half a day, so not a connection we count.