CK 225 then UA 5646 at O'Hare
Seattle (SEA) → Chicago → Sioux Falls
Timetable, Chicago time
07:42CK 225 from Seattle (SEA) at the gate
19:45UA 5646 to Sioux Falls leaves the gate
12 h 03 apart on the timetable
UA 5646 leaves 12 h 03 after CK 225 arrives on the timetable: more than half a day, so not a connection we count.