AA 1997 then UA 5194 at O'Hare
St Louis → Chicago → Sioux City
Timetable, Chicago time
09:00AA 1997 from St Louis at the gate
00:00UA 5194 to Sioux City leaves the gate
15 h apart on the timetable, overnight
UA 5194 leaves 15 h after AA 1997 arrives on the timetable: more than half a day, so not a connection we count.