UA 3915 then AA 4271 at O'Hare
Miami → Chicago → Allentown
Timetable, Chicago time
22:25UA 3915 from Miami at the gate
19:53AA 4271 to Allentown leaves the gate
21 h 28 apart on the timetable, overnight
AA 4271 leaves 21 h 28 after UA 3915 arrives on the timetable: more than half a day, so not a connection we count.