One of the most lucrative quarters for the Atlantic City casino industry in decades just concluded in September, according to a financial report issued by the state Division of Gaming Enforcement on Monday. AC’s nine casinos collectively produced $310.8 million in gross operating profit, the highest quarterly figures in at least 10 years. That translates to a little more than double the $151 million of profit in the same quarter of 2020, and at least $50 million more than each of the “boom third quarters” of 2015 to 2019. Because July and August tend to be the seasonal industry’s biggest revenue months, that quarter is nearly always the largest profit producer of each calendar year.