ATLANTIC CITY — Atlantic City’s casinos saw their revenue decline slightly in May, down less than 1 percent compared to a year ago.

The eight casinos collectively won $219.8 million from gamblers, a decline of 0.6 percent compared to May 2015, a month with more weekend days.

“Gaming win fell slightly in May, but a quirk in the calendar masks the continued improvement in the revenue picture,” said Matt Levinson, chairman of the New Jersey Casino Control Commission. “It’s common knowledge that weekends are the busiest time for Atlantic City’s casinos and this year, May had four Fridays and four Saturdays compared to May 2015, which had five Fridays and five Saturdays. That alone is more than enough reason for a relatively flat performance for the month.”

Despite the unfavorable calendar, he noted, table games revenue was up 4.5 percent at the eight casinos, to $53.9 million. Slot machine winnings were $149.3 million, down 4.9 percent from May 2015.

Only two of the eight casinos saw increases in May, led by the Borgata, whose nearly $65 million was up nearly 16 percent. Bally’s was just barely up, by 0.2 percent, to $18.2 million. MGM Resorts and Boyd Gaming currently own the Borgata, but MGM Resorts is buying out Boyd Gaming’s stake.

The other six casinos saw monthly declines, from a 2 percent dip at Tropicana, which won $27 million, to 18.2 percent at the Trump Taj Mahal, which won $15.1 million.

Internet gambling continued to be a bright spot for New Jersey, increasing by 32.6 percent to $16.5 million.

Four of Atlantic City’s 12 casinos shut down in 2014; the surviving eight have seen their revenue and profitability begin to stabilize recently with less competition in the local market.

So far this year, Atlantic City’s casinos have won just over $1 billion, which is up by 3.3 percent compared with the same period in 2015.

But New Jersey voters will decide in November whether to authorize two new casinos in northern New Jersey near New York City. A report commissioned by a lobbying group against North Jersey casinos and released Monday predicts three to five of Atlantic City’s remaining casinos could be forced to close by the new in-state competition.