Pennsylvania's first slot-machine parlor, Mohegan Sun at Pocono Downs, is opening to the public — more than two years after the Legislature authorized gambling to raise money for property tax relief.

Thousands were expected to show up Tuesday, when the casino opens to offer all-hours legalized gambling in Pennsylvania.

The Mohegan American Indian tribe of Connecticut, owner of the Pocono Downs harness racing complex in Plains Township outside Wilkes-Barre, spent $70 million on a nicely appointed but no-frills slots parlor that includes two gambling floors with nearly 1,100 machines, a bar, and a food court with three restaurants.

"I think everybody is a little nervous but also very excited," said Robert Soper, Mohegan Sun's chief executive officer, who leads a casino staff of about 400. "It was never our goal — and frankly it was never that important to us — to open first, but certainly we are going to celebrate the fact."

Although Gov. Ed Rendell hailed the casino opening as an important first step in delivering property-tax relief to Pennsylvanians, casino opponents forecast an increase in crime and other social ills.

CasinoFreePa, an antigambling group, asked state Attorney General Tom Corbett on Monday to prevent Mohegan Sun and other Pennsylvania casinos from opening until his office investigates whether slot machines comply with fraud and consumer protection laws.

Dianne M. Berlin, the group's leader, predicted a host of negative consequences for areas of the state with casinos: "Crime, bankruptcies, divorce, people embezzling from their employers" to support their gambling addictions.

"I have story after story after story of real people who would not have done the things they did, but gambling became very convenient for them," she said. "Convenience gambling is the worst gambling."

Corbett's spokesman, Kevin Harley, said the office would investigate any consumer complaints after the casinos are open but that it is the responsibility of gambling regulators and state police to make sure the slot machines are working properly.

The Pennsylvania Gaming Control Board gave Mohegan Sun permission to open after successful dry runs on Friday and Sunday nights. The test nights, which featured an invitation-only crowd of gamblers, brought in a total of $95,049. Of that amount, 34 percent — or $32,317 — was earmarked for property-tax relief, as prescribed by state law.

The tribe, which operates one of the world's largest casinos in Connecticut and paid $280 million for Pocono Downs in 2004, plans a second phase of development that will nearly double the number of slot machines and add retail shops, a nightclub and other amenities. The tribe said Monday it is planning to roughly double the Connecticut casino's 1,200 hotel rooms and add to its more than 6,000 slot machines and its table games.

When the Pennsylvania casino is fully operational with 2,000 machines, the slots parlor projects it will gross $230 per machine, per day, for total annual revenues of $167.9 million.

Gambling regulators awarded conditional slots licenses to Mohegan Sun and five other horse racing tracks earlier this fall. It expects to award as many as six more licenses — one to an established resort and five to standalone slots parlors — in December.

The state plans to use gambling revenues to cut taxes for homeowners and workers who pay Philadelphia's wage tax, fatten horse racing purses, and support a rent rebate program for senior citizens.

"We have a brand-new industry in Pennsylvania," said gubernatorial spokeswoman Kate Philips, "and the value of it will be exceedingly evident over the coming months as people begin to get jobs in the gaming industry and over the coming years as they begin to see their property taxes reduced dramatically."

Under state law, slot machines can pay out a minimum of $85 for every $100 wagered, meaning that plenty of gamblers will leave Mohegan Sun on Tuesday with lighter wallets.

With the potential for a large opening-day crowd, casino officials warned they might have to ask late arrivals to return another time. Total capacity, including the racetrack side of the building, is 5,000; the casino itself holds about 3,600.

"If we do exceed the building limits, we may have to turn away people," Soper said.