AA 5021 then UA 3992 at Charlotte
St Louis → Charlotte → Houston
Timetable, Charlotte time
19:29AA 5021 from St Louis at the gate
16:53UA 3992 to Houston leaves the gate
21 h 24 apart on the timetable, overnight
UA 3992 leaves 21 h 24 after AA 5021 arrives on the timetable: more than half a day, so not a connection we count.