AA 9908 then UA 2857 at O'Hare
Milwaukee → Chicago → Denver
Timetable, Chicago time
13:50AA 9908 from Milwaukee at the gate
10:55UA 2857 to Denver leaves the gate
21 h 05 apart on the timetable, overnight
UA 2857 leaves 21 h 05 after AA 9908 arrives on the timetable: more than half a day, so not a connection we count.