UA 3910 then UA 1998 at Houston
Washington → Houston → Cincinnati
Timetable, Houston time
14:30UA 3910 from Washington at the gate
12:20UA 1998 to Cincinnati leaves the gate
21 h 50 apart on the timetable, overnight
UA 1998 leaves 21 h 50 after UA 3910 arrives on the timetable: more than half a day, so not a connection we count.