AA 4121 then AA 3974 at O'Hare
Green Bay → Chicago → Harrisburg
Timetable, Chicago time
07:27AA 4121 from Green Bay at the gate
10:35AA 3974 to Harrisburg leaves the gate
3 h 08 apart on the timetable
The last days
AA 4121 and AA 3974 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.