AA 725 then UA 3907 at O'Hare
Los Angeles → Chicago → Washington
Timetable, Chicago time
16:05AA 725 from Los Angeles at the gate
12:00UA 3907 to Washington leaves the gate
19 h 55 apart on the timetable, overnight
UA 3907 leaves 19 h 55 after AA 725 arrives on the timetable: more than half a day, so not a connection we count.