DL 2646 then AA 4783 at Boston
Chicago O'Hare → Boston → Harrisburg
Timetable, Boston time
23:08DL 2646 from Chicago O'Hare at the gate
21:03AA 4783 to Harrisburg leaves the gate
21 h 55 apart on the timetable, overnight
AA 4783 leaves 21 h 55 after DL 2646 arrives on the timetable: more than half a day, so not a connection we count.