UA 3873 then AA 2551 at Houston
Kansas City → Houston → Dallas-Fort Worth
Timetable, Houston time
10:47UA 3873 from Kansas City at the gate
06:00AA 2551 to Dallas-Fort Worth leaves the gate
19 h 13 apart on the timetable, overnight
AA 2551 leaves 19 h 13 after UA 3873 arrives on the timetable: more than half a day, so not a connection we count.