F9 4307 then DL 2570 at O'Hare
Baltimore → Chicago → Boston
Timetable, Chicago time
11:23F9 4307 from Baltimore at the gate
11:00DL 2570 to Boston leaves the gate
23 h 37 apart on the timetable, overnight
DL 2570 leaves 23 h 37 after F9 4307 arrives on the timetable: more than half a day, so not a connection we count.