Penn National Gaming's Hollywood Casino Perryville located near neighboring Delaware

Patrons of Maryland's first slots casino didn't have to wait for its grand opening to start gambling.

Thursday will mark the grand opening of Maryland’s first slots casino, the 1,500-machine Hollywood Casino Perryville.

Owned by Penn National Gaming and located near neighboring Delaware in the state’s northeast corner, the casino held a successful trial run on Saturday to benefit local charities and received its license on Sunday. On Monday the casino began accepting gamblers.

"We've been extremely busy," Marc DeLeo, a spokesman for the casino, told The Washington Post.

Thursday’s grand opening will be attended by Gov. Martin O'Malley, who got the casino plan moving by proposing a referendum back in November 2008 that succeeded in blocking a longstanding legislative stalemate over the issue.

A second Maryland facility, at Ocean Downs Racetrack on the Eastern Shore, is scheduled to open December 16 with 750 machines and expand in phases to 800.

In the meantime, the fate of the state's two largest casinos, in Anne Arundel County and Baltimore, remains in limbo. The former, slated for 4,750 machines, must survive a public vote on a zoning measure in November to move forward. In Baltimore, a state panel rejected the plans of a bidder who wanted to put a 3,750-machine casino downtown.

A second round of bids for a fifth facility, in western Maryland, is expected to be launched soon.