AA 4504 then UA 5855 at O'Hare
South Bend → Chicago → Oklahoma City
Timetable, Chicago time
18:35AA 4504 from South Bend at the gate
13:30UA 5855 to Oklahoma City leaves the gate
18 h 55 apart on the timetable, overnight
UA 5855 leaves 18 h 55 after AA 4504 arrives on the timetable: more than half a day, so not a connection we count.