AA 2779 then UA 3376 at O'Hare
Boston → Chicago → St Louis
Timetable, Chicago time
17:36AA 2779 from Boston at the gate
11:00UA 3376 to St Louis leaves the gate
17 h 24 apart on the timetable, overnight
UA 3376 leaves 17 h 24 after AA 2779 arrives on the timetable: more than half a day, so not a connection we count.