AA 2120 then AA 2642 at San Francisco
Dallas-Fort Worth → San Francisco → Chicago O'Hare
Timetable, San Francisco time
08:56AA 2120 from Dallas-Fort Worth at the gatealso IB 8018
15:18AA 2642 to Chicago O'Hare leaves the gatealso BA 5612, GF 6849
6 h 22 apart on the timetable
The last days
AA 2120 and AA 2642 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.