AA 2146 then DL 1556 at O'Hare
Boston → Chicago → Los Angeles
Timetable, Chicago time
08:00AA 2146 from Boston at the gate
07:45DL 1556 to Los Angeles leaves the gate
23 h 45 apart on the timetable, overnight
DL 1556 leaves 23 h 45 after AA 2146 arrives on the timetable: more than half a day, so not a connection we count.