AA 4721 then B6 1223 at JFK
Boston → New York → Los Angeles
Timetable, New York time
19:03AA 4721 from Boston at the gate
16:48B6 1223 to Los Angeles leaves the gate
21 h 45 apart on the timetable, overnight
B6 1223 leaves 21 h 45 after AA 4721 arrives on the timetable: more than half a day, so not a connection we count.