AA 873 then AA 3620 at O'Hare
Atlanta → Chicago → St Louis
Timetable, Chicago time
12:29AA 873 from Atlanta at the gate
15:26AA 3620 to St Louis leaves the gate
2 h 57 apart on the timetable
The last days
AA 873 and AA 3620 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.