AA 6255 then UA 5191 at O'Hare
Sioux Falls → Chicago → Lancaster
Timetable, Chicago time
17:29AA 6255 from Sioux Falls at the gate
08:50UA 5191 to Lancaster leaves the gate
15 h 21 apart on the timetable, overnight
UA 5191 leaves 15 h 21 after AA 6255 arrives on the timetable: more than half a day, so not a connection we count.