UA 3501 then AA 2748 at O'Hare
Kansas City → Chicago → Las Vegas
Timetable, Chicago time
17:05UA 3501 from Kansas City at the gate
11:00AA 2748 to Las Vegas leaves the gate
17 h 55 apart on the timetable, overnight
AA 2748 leaves 17 h 55 after UA 3501 arrives on the timetable: more than half a day, so not a connection we count.