B6 1554 then DL 1439 at Boston
Washington National → Boston → Tampa
Timetable, Boston time
13:34B6 1554 from Washington National at the gate
13:20DL 1439 to Tampa leaves the gate
23 h 46 apart on the timetable, overnight
DL 1439 leaves 23 h 46 after B6 1554 arrives on the timetable: more than half a day, so not a connection we count.