UA 3874 then AA 936 at O'Hare
Chicago Rockford → Chicago → Dallas-Fort Worth
Timetable, Chicago time
01:21UA 3874 from Chicago Rockford at the gate
17:59AA 936 to Dallas-Fort Worth leaves the gate
16 h 38 apart on the timetable
AA 936 leaves 16 h 38 after UA 3874 arrives on the timetable: more than half a day, so not a connection we count.