user: Question: On what date was the attendance of the crowd 78,431?
Columns: ['Week', 'Date', 'Opponent', 'Result', 'Attendance']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'September 12, 2004', 'at Denver Broncos', 'L 34–24', '75,939']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Attendance" = '78,431';