UA 3375 then DL 1564 at O'Hare
St Louis → Chicago → Seattle (SEA)
Timetable, Chicago time
13:30UA 3375 from St Louis at the gate
12:00DL 1564 to Seattle (SEA) leaves the gate
22 h 30 apart on the timetable, overnight
DL 1564 leaves 22 h 30 after UA 3375 arrives on the timetable: more than half a day, so not a connection we count.