AA 9908 then UA 638 at O'Hare
Milwaukee → Chicago → San Francisco
Timetable, Chicago time
13:50AA 9908 from Milwaukee at the gate
12:42UA 638 to San Francisco leaves the gate
22 h 52 apart on the timetable, overnight
UA 638 leaves 22 h 52 after AA 9908 arrives on the timetable: more than half a day, so not a connection we count.