AA 3324 then 1I 605 at O'Hare
Boston → Chicago → St Louis
Timetable, Chicago time
08:00AA 3324 from Boston at the gate
11:301I 605 to St Louis leaves the gate
3 h 30 apart on the timetable
The last days
AA 3324 and 1I 605 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.