About a quarter of the casino jobs that propped up Atlantic City, N.J., for more than three decades are on the line as one gambling house closed in January, two more plan to in the next two months and a fourth — the $2.4 billion Revel that promised to transform the town from a bastion of gamblers into a destination for the glitterati — is seeking a buyer in bankruptcy, Bloomberg News reported today. Once the East Coast’s gambling hub, Atlantic City has suffered as casinos opened in neighboring states including Pennsylvania and New York after they legalized gambling or expanded betting to increase tax revenue. Even as Caesars Entertainment Corp. plans to close its money-losing Showboat casino in New Jersey, it’s opening the Horseshoe in Baltimore next month. The city’s 11 gambling houses account for almost half its jobs: 5,883 positions in a workforce of 13,500. The Atlantic Club closed in January, putting 1,600 people out of work. The shuttering of Caesars’ Showboat on Aug. 31 will wipe out 2,133 jobs. Trump Plaza Hotel & Casino said it plans to close Sept. 16, taking away another 1,009. Revel employs 3,106 people. About one-fifth of the 30,000 people registered as casino workers with the state Division of Gaming Enforcement live in Atlantic City, the most in a single zip code.