EI 123 then UA 3907 at O'Hare
Dublin → Chicago → Washington
Timetable, Chicago time
14:10EI 123 from Dublin at the gate
12:00UA 3907 to Washington leaves the gate
21 h 50 apart on the timetable, overnight
UA 3907 leaves 21 h 50 after EI 123 arrives on the timetable: more than half a day, so not a connection we count.