UA 511 then UA 3376 at O'Hare
Washington National → Chicago → St Louis
Timetable, Chicago time
14:27UA 511 from Washington National at the gate
11:00UA 3376 to St Louis leaves the gate
20 h 33 apart on the timetable, overnight
UA 3376 leaves 20 h 33 after UA 511 arrives on the timetable: more than half a day, so not a connection we count.