AA 9950 then AA 2748 at O'Hare
Philadelphia → Chicago → Las Vegas
Timetable, Chicago time
13:49AA 9950 from Philadelphia at the gate
11:00AA 2748 to Las Vegas leaves the gate
21 h 11 apart on the timetable, overnight
AA 2748 leaves 21 h 11 after AA 9950 arrives on the timetable: more than half a day, so not a connection we count.