UA 4258 then DL 1787 at Dulles
Cincinnati → Washington → Detroit
Timetable, Washington time
21:22UA 4258 from Cincinnati at the gate
17:13DL 1787 to Detroit leaves the gate
19 h 51 apart on the timetable, overnight
DL 1787 leaves 19 h 51 after UA 4258 arrives on the timetable: more than half a day, so not a connection we count.