CV 251 then UA 4572 at O'Hare
Anchorage → Chicago → Sioux Falls
Timetable, Chicago time
21:32CV 251 from Anchorage at the gate
12:29UA 4572 to Sioux Falls leaves the gate
14 h 57 apart on the timetable, overnight
UA 4572 leaves 14 h 57 after CV 251 arrives on the timetable: more than half a day, so not a connection we count.