DL 2879 then AA 1173 at O'Hare
Atlanta → Chicago → Pittsburgh
Timetable, Chicago time
19:05DL 2879 from Atlanta at the gate
18:30AA 1173 to Pittsburgh leaves the gate
23 h 25 apart on the timetable, overnight
AA 1173 leaves 23 h 25 after DL 2879 arrives on the timetable: more than half a day, so not a connection we count.