AA 3664 then UA 5191 at O'Hare
Buffalo → Chicago → Lancaster
Timetable, Chicago time
12:29AA 3664 from Buffalo at the gate
08:50UA 5191 to Lancaster leaves the gate
20 h 21 apart on the timetable, overnight
UA 5191 leaves 20 h 21 after AA 3664 arrives on the timetable: more than half a day, so not a connection we count.