AA 9866 then UA 638 at O'Hare
Bloomington-Normal → Chicago → San Francisco
Timetable, Chicago time
13:11AA 9866 from Bloomington-Normal at the gate
12:42UA 638 to San Francisco leaves the gate
23 h 31 apart on the timetable, overnight
UA 638 leaves 23 h 31 after AA 9866 arrives on the timetable: more than half a day, so not a connection we count.