AA 1597 then AA 3898 at DFW
New York LaGuardia → Dallas-Fort Worth → Brownsville
Timetable, Dallas-Fort Worth time
09:00AA 1597 from New York LaGuardia at the gate
21:20AA 3898 to Brownsville leaves the gate
12 h 20 apart on the timetable
AA 3898 leaves 12 h 20 after AA 1597 arrives on the timetable: more than half a day, so not a connection we count.