AA 2537 then UA 4789 at O'Hare
Tucson → Chicago → Fargo
Timetable, Chicago time
20:15AA 2537 from Tucson at the gate
19:45UA 4789 to Fargo leaves the gate
23 h 30 apart on the timetable, overnight
UA 4789 leaves 23 h 30 after AA 2537 arrives on the timetable: more than half a day, so not a connection we count.