UA 3911 then AA 1802 at O'Hare
Portland (Oregon) → Chicago → San Diego
Timetable, Chicago time
17:09UA 3911 from Portland (Oregon) at the gate
10:03AA 1802 to San Diego leaves the gate
16 h 54 apart on the timetable, overnight
AA 1802 leaves 16 h 54 after UA 3911 arrives on the timetable: more than half a day, so not a connection we count.