UA 2647 then DL 508 at Boston
San Francisco → Boston → Los Angeles
Timetable, Boston time
16:49UA 2647 from San Francisco at the gate
16:15DL 508 to Los Angeles leaves the gate
23 h 26 apart on the timetable, overnight
DL 508 leaves 23 h 26 after UA 2647 arrives on the timetable: more than half a day, so not a connection we count.