AA 4504 then UA 4481 at O'Hare
South Bend → Chicago → Tulsa
Timetable, Chicago time
18:35AA 4504 from South Bend at the gate
15:35UA 4481 to Tulsa leaves the gate
21 h apart on the timetable, overnight
UA 4481 leaves 21 h after AA 4504 arrives on the timetable: more than half a day, so not a connection we count.