AA 642 then UA 2050 at O'Hare
Dallas-Fort Worth → Chicago → Denver
Timetable, Chicago time
13:10AA 642 from Dallas-Fort Worth at the gate
13:00UA 2050 to Denver leaves the gate
23 h 50 apart on the timetable, overnight
UA 2050 leaves 23 h 50 after AA 642 arrives on the timetable: more than half a day, so not a connection we count.