UA 3532 then AA 2604 at O'Hare
Knoxville → Chicago → Austin
Timetable, Chicago time
18:43UA 3532 from Knoxville at the gate
13:24AA 2604 to Austin leaves the gate
18 h 41 apart on the timetable, overnight
AA 2604 leaves 18 h 41 after UA 3532 arrives on the timetable: more than half a day, so not a connection we count.