UA 4183 then AA 9912 at O'Hare
St Louis → Chicago → Richmond
Timetable, Chicago time
10:04UA 4183 from St Louis at the gate
07:30AA 9912 to Richmond leaves the gate
21 h 26 apart on the timetable, overnight
AA 9912 leaves 21 h 26 after UA 4183 arrives on the timetable: more than half a day, so not a connection we count.