AA 3487 then AA 1212 at O'Hare
Missoula → Chicago → Boston
Timetable, Chicago time
18:25AA 3487 from Missoula at the gate
19:13AA 1212 to Boston leaves the gate
48 min apart on the timetable
The last days
AA 3487 and AA 1212 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.