UA 3876 then AA 4527 at O'Hare
Miami → Chicago → Baltimore
Timetable, Chicago time
14:49UA 3876 from Miami at the gate
14:37AA 4527 to Baltimore leaves the gate
23 h 48 apart on the timetable, overnight
AA 4527 leaves 23 h 48 after UA 3876 arrives on the timetable: more than half a day, so not a connection we count.