AA 642 then UA 535 at O'Hare
Dallas-Fort Worth → Chicago → Houston
Timetable, Chicago time
13:10AA 642 from Dallas-Fort Worth at the gate
09:21UA 535 to Houston leaves the gate
20 h 11 apart on the timetable, overnight
UA 535 leaves 20 h 11 after AA 642 arrives on the timetable: more than half a day, so not a connection we count.