AA 3409 then UA 5201 at O'Hare
St Louis → Chicago → Milwaukee
Timetable, Chicago time
07:34AA 3409 from St Louis at the gate
20:00UA 5201 to Milwaukee leaves the gate
12 h 26 apart on the timetable
UA 5201 leaves 12 h 26 after AA 3409 arrives on the timetable: more than half a day, so not a connection we count.