UA 3501 then UA 646 at O'Hare
Kansas City → Chicago → Denver
Timetable, Chicago time
17:05UA 3501 from Kansas City at the gate
13:30UA 646 to Denver leaves the gate
20 h 25 apart on the timetable, overnight
UA 646 leaves 20 h 25 after UA 3501 arrives on the timetable: more than half a day, so not a connection we count.