UA 4592 then UA 5539 at O'Hare
St Louis → Chicago → Cleveland
Timetable, Chicago time
19:05UA 4592 from St Louis at the gate
10:50UA 5539 to Cleveland leaves the gate
15 h 45 apart on the timetable, overnight
UA 5539 leaves 15 h 45 after UA 4592 arrives on the timetable: more than half a day, so not a connection we count.