DL 1248 then UA 516 at Atlanta
Harrisburg → Atlanta → Chicago O'Hare
Timetable, Atlanta time
16:08DL 1248 from Harrisburg at the gate
15:32UA 516 to Chicago O'Hare leaves the gate
23 h 24 apart on the timetable, overnight
UA 516 leaves 23 h 24 after DL 1248 arrives on the timetable: more than half a day, so not a connection we count.