AA 642 then UA 4572 at O'Hare
Dallas-Fort Worth → Chicago → Sioux Falls
Timetable, Chicago time
13:10AA 642 from Dallas-Fort Worth at the gate
12:29UA 4572 to Sioux Falls leaves the gate
23 h 19 apart on the timetable, overnight
UA 4572 leaves 23 h 19 after AA 642 arrives on the timetable: more than half a day, so not a connection we count.