WITH AN AUDACIOUS midmorning fireworks display, an emotional speech from the mayor of Everett, and a crowd of thousands lined up in the hot sun, Encore Boston Harbor threw open its doors to the public on Sunday.

In his speech Sunday morning, Everett Mayor Carlo DeMaria referenced the bruising regulatory and legal challenges that Wynn Resorts had to hurdle to transform a polluted patch of shoreline on the Mystic River into a gleaming $2.6 billion casino – the first in metro Boston and the second in Massachusetts.

“My wife and I and my kids have endured so much through this process, and if it weren’t for my wife, we wouldn’t be here today. And I want to thank her for standing by my side,” DeMaria told the crowd, many of whom had been waiting hours to be among the first placing wagers at the resort.

Wynn Resorts CEO Matt Maddox recalled meeting with DeMaria on the site of a former Monsanto plant that had polluted the area with chemicals.

“I was standing on this site with the mayor – just us two – and there wasn’t a blade of grass on the site,” Maddox recalled. “Now there’s a thousand mature trees, 50,000 flowering plants, tens of thousands of shrubs, and a living shoreline for the first time in 100 years.”

Wynn Resorts CEO Matt Maddox spoke to the crowd gathered for the opening of Encore Boston Harbor. (Photo by Andy Metzger)

The smokestacks of the Mystic Generating Station still tower over the skyline nearby, but Wynn has designs on that property, and DeMaria said the casino – which has artificial grass but real trees and flowers – has transformed the area across the river from Charlestown.

“When you drive through Everett, you’ll no longer smell gas and sulphur and oils, but you’ll smell flowers, trees,” DeMaria said. “We will no longer be the back door to the city of Boston. We will now be the front door to the city of Everett.”

After the speeches, barges floating in the water at low tide shot off colorful fireworks that were barely visible against the bright summer sky.

Encore had predicted roughly 50,000 visitors for Sunday, which could put a strain on the local transportation infrastructure, but there was no gridlock in the morning.

“Not too much traffic. We were shocked,” said Cathy Saffelo, a Somerville resident who parked in Somerville, and then walked to the casino.

“No traffic at all,” said John Feloni, who drove in from Somerville.

Rob Skilling, who lives in southern New Hampshire, said he left his house at around 5 a.m. and pulled into a parking garage about 45 minutes later. He was early enough to be one of the first people in line.

One man who declined to provide his name said that he took the Orange Line from the South End to a waiting shuttle at Wellington, describing the whole trip as “very efficient.” The man said he has gambled often at the Connecticut casinos but won’t anymore with a casino so conveniently located.

Elaine Wynn was feted at the opening of Encore Boston Harbor. (Photo by Andy Metzger)

The off-ramp from Interstate 93 to nearby Sullivan Square was practically empty, and there was traffic on Route 99 in front of the casino, but it wasn’t jammed. The next big test, transportation-wise, will come tomorrow when the casino’s second day in business will coincide with the first day of the work week.

After three test days last week, the Massachusetts Gaming Commission gave Encore approval to open to the public on Sunday, and the commission anticipates discussing a permanent certificate for casino operations at its meeting on Thursday.

The whole project was thrown into jeopardy when The Wall Street Journal in January 2018 exposed a lengthy history of allegations of sexual harassment and worse against Steve Wynn, who was then the company’s chairman and CEO. Steve Wynn resigned, and Wynn Resorts recently had to pay the Massachusetts Gaming Commission a fine of $35 million, with Maddox docked an additional $500,000, for the way he handled the situation.

Elaine Wynn, Steve Wynn’s ex-wife, who played a key role in bringing the old allegations to light, was feted at the casino opening. During his speech, DeMaria said he had enjoyed meeting her and other Wynn Resorts officials, telling them, “You’re wonderful people, and I’m so happy to be part of the organization.”

After the Gaming Commission levied the penalties on Wynn and Maddox, Wynn acknowledged to The Boston Globe that it had raised the possibility of selling the Everett casino to MGM, which opened the state’s first casino in Springfield last year. Maddox on Friday said the casino is not for sale, and DeMaria indicated he never had any doubt that Wynn Resorts would be the parent company for the Everett resort.

“This was always going to stay a Wynn and part of the Wynn collection. It was never going anywhere else. There was a promise made to me by a certain fellow that said ‘We’re partners for life, and our company’s going to be part of your community,’” DeMaria said. “I’m that type of guy. When someone gives me their word, I figure we’re partners. We’re not going anywhere.”

The casino, which is the product of the 2011 state gaming law, plans to employ 5,800 people, and it could have broader implications on the regional economy. Middlesex County Sheriff Peter Koutoujian on Saturday announced the completion of a three-year gambling survey of 5,000 people entering the jail or house of correction. The study found only 20 percent of respondents said they gamble – compared to 70 percent of the state as a whole, according to a different study. Only 1.3 percent of the inmates and detainees reported their last betting experience took place online or at a casino, but those who had recently bet at a casino reported spending much more on gambling than those who played the lottery.

“With the introduction of expanded gaming in the Commonwealth, it is crucial to establish the level to which those in our custody are involved in gaming,” said Koutoujian in a statement. “Because just as substance use, mental illness, homelessness and educational deficiencies can contribute to incarceration – so too, can gambling.  Understanding who is in our custody and the underlying factors that lead them to us is critical to enhancing public safety.”