UA 415 then UA 3376 at O'Hare
Milan → Chicago → St Louis
Timetable, Chicago time
18:15UA 415 from Milan at the gate
11:00UA 3376 to St Louis leaves the gate
16 h 45 apart on the timetable, overnight
UA 3376 leaves 16 h 45 after UA 415 arrives on the timetable: more than half a day, so not a connection we count.