UA 3874 then AA 791 at O'Hare
Chicago Rockford → Chicago → Miami
Timetable, Chicago time
01:21UA 3874 from Chicago Rockford at the gate
14:30AA 791 to Miami leaves the gate
13 h 09 apart on the timetable
AA 791 leaves 13 h 09 after UA 3874 arrives on the timetable: more than half a day, so not a connection we count.