UA 539 then AA 1254 at DFW
Chicago O'Hare → Dallas-Fort Worth → Nashville
Timetable, Dallas-Fort Worth time
09:40UA 539 from Chicago O'Hare at the gate
07:30AA 1254 to Nashville leaves the gate
21 h 50 apart on the timetable, overnight
AA 1254 leaves 21 h 50 after UA 539 arrives on the timetable: more than half a day, so not a connection we count.