UA 4576 then UA 5539 at O'Hare
Greensboro → Chicago → Cleveland
Timetable, Chicago time
19:00UA 4576 from Greensboro at the gate
10:50UA 5539 to Cleveland leaves the gate
15 h 50 apart on the timetable, overnight
UA 5539 leaves 15 h 50 after UA 4576 arrives on the timetable: more than half a day, so not a connection we count.