UA 5974 then AA 3974 at O'Hare
Duluth → Chicago → Harrisburg
Timetable, Chicago time
08:29UA 5974 from Duluth at the gate
08:27AA 3974 to Harrisburg leaves the gate
23 h 58 apart on the timetable, overnight
AA 3974 leaves 23 h 58 after UA 5974 arrives on the timetable: more than half a day, so not a connection we count.