AA 9909 then UA 1651 at Denver
Los Angeles → Denver → Chicago O'Hare
Timetable, Denver time
16:45AA 9909 from Los Angeles at the gate
15:01UA 1651 to Chicago O'Hare leaves the gate
22 h 16 apart on the timetable, overnight
UA 1651 leaves 22 h 16 after AA 9909 arrives on the timetable: more than half a day, so not a connection we count.