UA 3874 then AA 6459 at O'Hare
Chicago Rockford → Chicago → Kansas City
Timetable, Chicago time
01:21UA 3874 from Chicago Rockford at the gate
16:59AA 6459 to Kansas City leaves the gate
15 h 38 apart on the timetable
AA 6459 leaves 15 h 38 after UA 3874 arrives on the timetable: more than half a day, so not a connection we count.