AA 1204 then UA 3519 at O'Hare
Miami → Chicago → Milwaukee
Timetable, Chicago time
07:42AA 1204 from Miami at the gate
19:45UA 3519 to Milwaukee leaves the gate
12 h 03 apart on the timetable
UA 3519 leaves 12 h 03 after AA 1204 arrives on the timetable: more than half a day, so not a connection we count.