AA 3247 then DL 2646 at Boston
Miami → Boston → Chicago O'Hare
Timetable, Boston time
13:23AA 3247 from Miami at the gate
16:35DL 2646 to Chicago O'Hare leaves the gate
3 h 12 apart on the timetable
The last days
AA 3247 and DL 2646 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.