UA 2138 then BR 643 at O'Hare
St Louis → Chicago → Anchorage
Timetable, Chicago time
14:35UA 2138 from St Louis at the gate
11:55BR 643 to Anchorage leaves the gate
21 h 20 apart on the timetable, overnight
BR 643 leaves 21 h 20 after UA 2138 arrives on the timetable: more than half a day, so not a connection we count.