AA 581 then UA 3395 at O'Hare
Miami → Chicago → St Louis
Timetable, Chicago time
09:30AA 581 from Miami at the gate
13:00UA 3395 to St Louis leaves the gate
3 h 30 apart on the timetable
The last days
AA 581 and UA 3395 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.