UA 2638 then UA 3754 at Houston
Chicago → Houston → Waco
Timetable, Houston time
13:35UA 2638 from Chicago at the gate
11:30UA 3754 to Waco leaves the gate
21 h 55 apart on the timetable, overnight
UA 3754 leaves 21 h 55 after UA 2638 arrives on the timetable: more than half a day, so not a connection we count.