AA 4504 then UA 1732 at O'Hare
South Bend → Chicago → Las Vegas
Timetable, Chicago time
18:35AA 4504 from South Bend at the gate
16:15UA 1732 to Las Vegas leaves the gate
21 h 40 apart on the timetable, overnight
UA 1732 leaves 21 h 40 after AA 4504 arrives on the timetable: more than half a day, so not a connection we count.