DL 9975 then AA 3324 at Boston
Miami (MIA) → Boston → Chicago O'Hare
Timetable, Boston time
02:50DL 9975 from Miami (MIA) at the gate
05:54AA 3324 to Chicago O'Hare leaves the gate
3 h 04 apart on the timetable
Boston’s board gives an arrival time for only about 59% of its flights, so many days show no gate time.
The last days
DL 9975 and AA 3324 weren’t both flown 15 min to 12 h apart in the last 21 days.
Statistics from past flights, not live flight information. Always check times and your connection with your airline, and don’t base travel or booking decisions on these numbers.