UA 5664 then UA 3907 at Houston
Amarillo → Houston → Washington
Timetable, Houston time
11:03UA 5664 from Amarillo at the gate
07:00UA 3907 to Washington leaves the gate
19 h 57 apart on the timetable, overnight
UA 3907 leaves 19 h 57 after UA 5664 arrives on the timetable: more than half a day, so not a connection we count.