AA 6468 then BR 643 at O'Hare
St Louis → Chicago → Anchorage
Timetable, Chicago time
15:03AA 6468 from St Louis at the gate
11:55BR 643 to Anchorage leaves the gate
20 h 52 apart on the timetable, overnight
BR 643 leaves 20 h 52 after AA 6468 arrives on the timetable: more than half a day, so not a connection we count.