AA 6283 then UA 3907 at O'Hare
Des Moines → Chicago → Washington
Timetable, Chicago time
15:44AA 6283 from Des Moines at the gate
12:00UA 3907 to Washington leaves the gate
20 h 16 apart on the timetable, overnight
UA 3907 leaves 20 h 16 after AA 6283 arrives on the timetable: more than half a day, so not a connection we count.