Maine’s summer tourism-related revenue was on track at the end of August to break all previous records, driven largely by strong sales in Portland, the southern coast and Bar Harbor.

However, restaurant and lodging professionals noted that not all tourism-related businesses across the state have benefited equally from the boom.

Summer 2015 was a record season for Maine tourism, but in summer 2016, Maine’s restaurant sales of $1.11 billion for the four months ending Aug. 30 were up nearly 5 percent from the same period year earlier. And its lodging sales of $559.3 million for the four months were up more than 7 percent from the same period of 2015, according to Maine Revenue Services data. Figures for August are preliminary, and September figures are not yet available.

The numbers reflect the highest summer revenues for both industries in Maine’s history.

“It’s very positive data,” said Steve Hewins, president and CEO of the Maine restaurant and innkeepers associations. “I’m cautiously optimistic that we will maybe reach an annual record for the end of the year.”

Hewins said robust sales in the Bar Harbor region contributed significantly to the revenue growth, as visitors came out to celebrate the 100th anniversary of Acadia National Park.

Other areas of Maine, such as the midcoast, did not see the same level of business that Bar Harbor and southern Maine enjoyed, he said.

“Just know that it’s not straight across Maine that these numbers are up,” Hewins said.

Jean Ginn Marvin, innkeeper at The Nonantum Resort in Kennebunkport, said 2016 has been “a banner year” for summer visitors. The resort’s wedding business alone has eclipsed all previous years, she said.

Ginn Marvin said a trend toward shorter stays has worked to the Nonantum’s benefit, as it is the ideal distance from the Boston area for a two- or three-day vacation.

“Because of our proximity to the Boston market, it makes an easy transition for a couple of days,” she said.

However, Ginn Martin said some of the smaller inns in and around Kennebunkport have experienced a decline in sales this summer. She attributed the slump to the growing popularity of short-term rental services such as Airbnb.

“The weekends are still strong, but during the week it’s not strong at all” for some smaller inns and bed-and-breakfasts, she said.

Consistently higher traffic volume on the Maine Turnpike is another sign that summer tourism activity is up, said Maine Turnpike Authority Executive Director Peter Mills.

“We knew in June and July that tourism was going to be big,” Mills said. “And it’s also reinforced by the volume of delivery trucks. It was very heavy in the spring.”

Mills said year-over-year traffic volume on the turnpike has been up 4 to 5 percent for every single month so far in 2016, regardless of weather conditions.

“We haven’t had any ups-and-downs,” he said. “It’s been all ups.”

Hewins said the Maine tourism industry’s future growth is likely to be limited only by the availability of hotel and restaurant workers. Some businesses already are struggling to maintain a full staff during the busiest months, he said, and many positions once considered seasonal are now needed year-round.

Hewins called on Maine officials to support educational programs that produce local hospitality workers, and visa programs that bring in more workers from abroad. He said robust tourism activity boosts the entire state economy and benefits a wide variety of businesses.

“We need to support the growth of this industry,” Hewins said.