AA 3845 then UA 3636 at O'Hare
Springfield (SPI) → Chicago → Knoxville
Timetable, Chicago time
07:29AA 3845 from Springfield (SPI) at the gate
07:07UA 3636 to Knoxville leaves the gate
23 h 38 apart on the timetable, overnight
UA 3636 leaves 23 h 38 after AA 3845 arrives on the timetable: more than half a day, so not a connection we count.