UA 2120 then AA 591 at Denver
Newark → Denver → Charlotte
Timetable, Denver time
15:48UA 2120 from Newark at the gate
15:41AA 591 to Charlotte leaves the gate
23 h 53 apart on the timetable, overnight
AA 591 leaves 23 h 53 after UA 2120 arrives on the timetable: more than half a day, so not a connection we count.