UA 3874 then AA 3186 at O'Hare
Chicago → Chicago → New York LaGuardia
Timetable, Chicago time
01:21UA 3874 from Chicago at the gate
15:40AA 3186 to New York LaGuardia leaves the gate
14 h 19 apart on the timetable
AA 3186 leaves 14 h 19 after UA 3874 arrives on the timetable: more than half a day, so not a connection we count.