B6 1397 then DL 1554 at Atlanta
Boston → Atlanta → Washington
Timetable, Atlanta time
15:59B6 1397 from Boston at the gate
15:27DL 1554 to Washington leaves the gate
23 h 28 apart on the timetable, overnight
DL 1554 leaves 23 h 28 after B6 1397 arrives on the timetable: more than half a day, so not a connection we count.