AA 4478 then UA 4789 at O'Hare
Portland (Maine) → Chicago → Fargo
Timetable, Chicago time
19:55AA 4478 from Portland (Maine) at the gate
19:45UA 4789 to Fargo leaves the gate
23 h 50 apart on the timetable, overnight
UA 4789 leaves 23 h 50 after AA 4478 arrives on the timetable: more than half a day, so not a connection we count.