CZ 427 then UA 5021 at O'Hare
Anchorage → Chicago → Sioux City
Timetable, Chicago time
18:22CZ 427 from Anchorage at the gate
16:20UA 5021 to Sioux City leaves the gate
21 h 58 apart on the timetable, overnight
UA 5021 leaves 21 h 58 after CZ 427 arrives on the timetable: more than half a day, so not a connection we count.