UA 3874 then AA 6346 at O'Hare
Chicago Rockford → Chicago → Lexington
Timetable, Chicago time
01:21UA 3874 from Chicago Rockford at the gate
15:45AA 6346 to Lexington leaves the gate
14 h 24 apart on the timetable
AA 6346 leaves 14 h 24 after UA 3874 arrives on the timetable: more than half a day, so not a connection we count.