UA 5424 then UA 2000 at O'Hare
Washington National → Chicago → St Louis
Timetable, Chicago time
14:33UA 5424 from Washington National at the gate
14:12UA 2000 to St Louis leaves the gate
23 h 39 apart on the timetable, overnight
UA 2000 leaves 23 h 39 after UA 5424 arrives on the timetable: more than half a day, so not a connection we count.