UA 3985 then UA 3907 at Houston
Des Moines → Houston → Washington
Timetable, Houston time
10:40UA 3985 from Des Moines at the gate
07:00UA 3907 to Washington leaves the gate
20 h 20 apart on the timetable, overnight
UA 3907 leaves 20 h 20 after UA 3985 arrives on the timetable: more than half a day, so not a connection we count.