UA 3902 then AA 2748 at O'Hare
Rio De Janeiro → Chicago → Las Vegas
Timetable, Chicago time
17:01UA 3902 from Rio De Janeiro at the gate
11:00AA 2748 to Las Vegas leaves the gate
17 h 59 apart on the timetable, overnight
AA 2748 leaves 17 h 59 after UA 3902 arrives on the timetable: more than half a day, so not a connection we count.