There are more tourists filling more Las Vegas-area hotel rooms than ever before. Yet, the coming national holiday reflects a pair of challenges facing the city’s hotel-casino operators.

First, there’s the calendar, which has July Fourth falling on a Wednesday. Does the holiday begin this weekend and end Wednesday or does it begin midweek and end the following weekend?

The Las Vegas Convention and Visitors Authority expects 275,000 visitors to come to the region during the holiday, which the authority says begins with the Fourth of July.

The 269,000 people who descended on the city last year had the Fourth fall on a Tuesday, at the end of their stay. “What’s the weekend?” pondered one tourism industry executive. “I don’t know.”

The same calendar that robs many workers of a three-day getaway will likely cut into the holiday visits of tens of thousands of tourists, according to Strip executives and industry observers. That could mean lower hotel occupancy and room rates, and less gaming revenue than many casinos would record on an average Fourth of July weekend.

“It’s less than ideal,” said Rob Stillwell, a Boyd Gaming vice president, whose company owns and operates the Stardust, Main Street Station and Sam’s Town, among its holdings. Then, there are the ups and downs of the national and regional economies.

The latest theory making the rounds of Strip and Wall Street offices holds that the uncertain national economy, rising energy and gasoline prices, job layoffs, and the spread of tribal and riverboat gambling have cut into the amount of money many tourists are spending in Las Vegas.

They’re still coming in record numbers. As many as 37 million visitors could hit the desert city this year, up from 35.8 million last year. But the purveyors of the more-is-less theory point to recent slot revenues as proof.

The machines are considered one of the truest gauges of mid-market tourist play in the state. If those fanny-pack-wearing visitors are worried about the economy, the thinking goes, they’ll spend less on Wheel of Fortune, Monopoly and Megabucks, among other games.

The statewide slot win for casinos was up less than 3 percent in January, down slightly in February, virtually flat in March and up 5.5 percent in April, creating a revenue roller coaster of uncertainty.

“You would expect to see some declines given all of the pressure on customers’ discretionary income,” Stillwell said. MGM Mirage’s three casinos at Primm have witnessed that fall-off in slot play among drop-in visitors, said Primadonna Resorts President George Boyer, who declined to cite specific figures.

The trio of hotel-casinos have increased their advertising efforts through direct mail, billboards and radio spots, which air in Southern California. “We have a range of strategies in place to recapture that business,” Boyer said.

Despite the midmarket uncertainty, the operators of high-end properties expect July Fourth results to be strong. Meantime, the city’s marketing arm, the Las Vegas Convention and Visitors Authority, offers an upbeat assessment of the coming weekend, with a caveat.

“There’s no doubt if you pick any weekday to have the Fourth, the middle of the week would not be the day,” authority spokesman Rob Powers said. “But any projections of gloom and doom are grossly overstating the holiday we’re going to have. The town is going to be full. I would venture to say a lot of people will be taking Thursday and Friday off next week.”