DL 169 then DL 1724 at Boston
Barcelona → Boston → Chicago O'Hare
Timetable, Boston time
13:41DL 169 from Barcelona at the gate
16:25DL 1724 to Chicago O'Hare leaves the gate
2 h 44 apart on the timetable
The last days
DL 169 and DL 1724 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.