UA 3874 then AS 337 at O'Hare
Chicago → Chicago → Seattle (SEA)
Timetable, Chicago time
01:21UA 3874 from Chicago at the gate
17:46AS 337 to Seattle (SEA) leaves the gate
16 h 25 apart on the timetable
AS 337 leaves 16 h 25 after UA 3874 arrives on the timetable: more than half a day, so not a connection we count.