AA 642 then UA 1117 at O'Hare
Dallas-Fort Worth → Chicago → Boston
Timetable, Chicago time
13:10AA 642 from Dallas-Fort Worth at the gate
09:13UA 1117 to Boston leaves the gate
20 h 03 apart on the timetable, overnight
UA 1117 leaves 20 h 03 after AA 642 arrives on the timetable: more than half a day, so not a connection we count.