AA 3358 then UA 5207 at O'Hare
Sioux Falls → Chicago → Denver
Timetable, Chicago time
14:11AA 3358 from Sioux Falls at the gate
21:00UA 5207 to Denver leaves the gate
6 h 49 apart on the timetable
The last days
AA 3358 and UA 5207 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.