General manager Eric Althaus said the casino has intentionally overstaffed by about two dozen new hires to prepare for peak traffic, noting that March is typically among the busier months for those in the gaming industry.

“We’re in a really good spot right now,” Althaus said Tuesday night, as he sat on one of the plush blue couches that face a two-story TV screen dedicated to sporting events. “But we still have open positions. So anyone that’s looking for a job, by all means, go online and we can start those conversations.”

The Nash, which is operated by ECL Entertainment, isn’t the only casino making big investments within a short drive of the state line. Just about every casino operator in New Hampshire has moved to expand since the state legalized historic horse racing machines in 2021, according to a 2024 market analysis by Spectrum Gaming Group.

While historic horse racing machines look similar to slot machines, their outcomes are based on decades of actual horse race results rather than random numbers.

“Every once in a while, you’ll see somebody playing a game and up at the top you’ll see an actual horse race run across the screen,” said Sheila M. Doherty of Nashua, a player who likes to try her luck on those machines and also on the roulette wheel.

Doherty, who attended a “soft opening” event Tuesday night before the grand opening on Wednesday morning, said The Nash has an impressive variety of games, including some that even she hadn’t seen elsewhere. (She laughed as she said she’s visited “a lot of casinos.”)

Since slot machines still aren’t allowed in New Hampshire, the legalization of historic horse racing machines offered an opportunity for existing race tracks and smaller mom-and-pop gaming operations to expand.

The former Seabrook Greyhound Park became The Brook, which debuted the historic horse racing games in 2022 and embarked on a series of renovations, with further expansion planned. Other gambling businesses, including the Gate City Casino in Nashua and Revo Casino and Social House in Dover, have tackled expansions of their own, and plans are in motion for a massive overhaul of the Hampton Beach Casino as well.

Some have repurposed older or underused buildings rather than starting from scratch. In Rochester, the Lilac Club Casino is slated to open next week in what had been a small, long-neglected mall. And in Salem, a casino is being developed in a former Lord & Taylor department store at The Mall at Rockingham Park.

The growth spurt has come as New Hampshire effectively took a free-market approach to casinos, without imposing additional limits on the number, size, or location of such venues, according to the Spectrum Gaming Group analysis. While the rest of New England had a combined total of nine casinos, as of last year, New Hampshire alone had 10 casinos with historic horse racing machines, according to the analysis. Most aren’t nearly as big as The Nash, and the state has imposed a moratorium on new licenses.

Concerns about problem gambling, addiction, and other negative social impacts associated with casinos have spilled over the state line. City councilors in Lawrence, Mass., passed a resolution last fall saying the planned casino in Salem, N.H., would rely heavily on “targeting the financial desperation of Lawrence’s low-income workers, elderly, and disabled” community members. Salem’s planning board signed off on the project in December anyway.

In Nashua, where the new casino is just about as close to the state line as is physically possible, some local leaders voiced practical concerns about potential jurisdictional complications whenever a law enforcement matter crosses from the casino floor in New Hampshire to the parking lot in Massachusetts.

Nashua Alderman Patricia S. Klee said she has nothing against casinos but worried police might encounter challenges in court stemming from the adult entertainment venue having been placed adjacent to the state line. The Nash isn’t like Sears, she noted.

“This place is going to be open till the wee hours of the morning, where people are drinking … so it’s a completely different type of business,” she said.

The Nash, which will open at 9 a.m. every day, will close at 2 a.m. on Sundays through Thursdays and 4 a.m. on Fridays and Saturdays, with no alcoholic drinks served after 1:30 a.m.

Althaus, the general manager, said The Nash has prioritized safety and security for visitors and casino employees. The facility has high-power security systems, police details with both Nashua and Tyngsborough, and safety plans, he said.

Tyngsborough Police Chief Shaun Woods said the two municipalities have a mutual aid agreement in place that allows officers to collaborate across state lines.

The economic upsides that The Nash expects to contribute to the local economy include both a boost to tourism-related tax revenues and charitable contributions.

All casinos in New Hampshire are charitable gaming establishments, meaning they must contribute a share of their revenues to nonprofit organizations. The state stipulates that charities be given 35 percent of the revenue from table games and 8.75 percent of the revenue from historic horse racing machines. On top of that, the state takes 10 percent and 16.25 percent, respectively.

Because of the state’s charitable gaming rules, The Nash projects that it will generate nearly $24 million each year for 104 nonprofits.

Matthew R. Fentross, executive director of the Nashua Children’s Home — which is one of the two nonprofits designated to receive a share of The Nash’s revenues for the current week — said his organization has received $20,000 to $30,000 in charitable gaming revenues in past years from a smaller casino, so this year’s haul will likely be much larger.

Only two of the three programs operated by the Nashua Children’s Home receive funding through government contracts, Fentross said. The third program, which provides transitional living support for young adults, relies on contributions from the public and from charitable gaming, he said.

“That program prevents homelessness for kids who are aging out of residential care, 18 to 22 years old,” he said. “So we provide affordable housing, some job coaching, and assistive programs to help them into adulthood.”

Fentross said the charitable gaming revenue is a significant help for his nonprofit and many others in New Hampshire.

“It’s huge,” he said.

Steven Porter can be reached at steven.porter@globe.com. Follow him @reporterporter.