AA 764 then UA 3874 at O'Hare
Houston → Chicago → LCQ
Timetable, Chicago time
11:58AA 764 from Houston at the gate
06:30UA 3874 to LCQ leaves the gate
18 h 32 apart on the timetable, overnight
UA 3874 leaves 18 h 32 after AA 764 arrives on the timetable: more than half a day, so not a connection we count.