AA 2253 then UA 3900 at San Francisco
Chicago O'Hare → San Francisco → Rio De Janeiro
Timetable, San Francisco time
16:22AA 2253 from Chicago O'Hare at the gatealso QF 4756
16:00UA 3900 to Rio De Janeiro leaves the gate
23 h 38 apart on the timetable, overnight
UA 3900 leaves 23 h 38 after AA 2253 arrives on the timetable: more than half a day, so not a connection we count.