AA 1204 then UA 5646 at O'Hare
Miami → Chicago → Sioux Falls
Timetable, Chicago time
07:42AA 1204 from Miami at the gate
19:45UA 5646 to Sioux Falls leaves the gate
12 h 03 apart on the timetable
UA 5646 leaves 12 h 03 after AA 1204 arrives on the timetable: more than half a day, so not a connection we count.