Newly released figures show Atlantic City's casinos shared the misery last month, with all 11 reporting revenue declines compared with May 2010.
Their combined revenue fell more than 9 percent from a year ago to $290.6 million.
The biggest loser was Trump Plaza Hotel Casino, down 25 percent.
Slot machine win fell 8.7 percent, to $206 million, while table game win decreased by 10.1 percent, to $84.6 million.
For the first five months of the year, casinos won $1.4 billion, down 7.6 percent from the same period in 2010.
Atlantic City is in the midst of a 4½-year revenue slump brought on by competition from casinos in neighboring states and the sluggish economy.