AA 3744 then DL 2570 at Boston
Washington National → Boston → Chicago O'Hare
Timetable, Boston time
12:10AA 3744 from Washington National at the gate
07:30DL 2570 to Chicago O'Hare leaves the gate
19 h 20 apart on the timetable, overnight
DL 2570 leaves 19 h 20 after AA 3744 arrives on the timetable: more than half a day, so not a connection we count.