AA 4448 then UA 3874 at O'Hare
Memphis → Chicago → LCQ
Timetable, Chicago time
08:47AA 4448 from Memphis at the gate
06:30UA 3874 to LCQ leaves the gate
21 h 43 apart on the timetable, overnight
UA 3874 leaves 21 h 43 after AA 4448 arrives on the timetable: more than half a day, so not a connection we count.