UA 3874 then AA 3559 at O'Hare
Chicago → Chicago → Moline
Timetable, Chicago time
01:21UA 3874 from Chicago at the gate
15:17AA 3559 to Moline leaves the gate
13 h 56 apart on the timetable
AA 3559 leaves 13 h 56 after UA 3874 arrives on the timetable: more than half a day, so not a connection we count.