AA 4504 then UA 719 at O'Hare
South Bend → Chicago → Denver
Timetable, Chicago time
18:35AA 4504 from South Bend at the gate
16:20UA 719 to Denver leaves the gate
21 h 45 apart on the timetable, overnight
UA 719 leaves 21 h 45 after AA 4504 arrives on the timetable: more than half a day, so not a connection we count.