ACADIA NATIONAL PARK, Maine — The estimated visitation total for Maine’s only national park in 2015 is the highest in the past 20 years, according to park officials.

Acadia had an estimated 2.81 million visits in 2015, park officials told Acadia’s citizen advisory commission Monday. The last time the park had an annual estimate of at least 2.8 million visits was in 1995, before Bill Clinton was re-elected as president. The estimated total for that year was 2.84 million.

The 2015 estimated visitation total, which counts repeat trips into the park by any one visitor as multiple visits, marks the second year in a row visits have increased at Acadia. The park had an estimated 2,563,000 visits in 2014, which represented an increase of more than 300,000 visits over 2013.

The park was officially closed for two weeks in October 2013 because of a federal government shutdown that resulted from a standoff in Congress over the federal budget.

The estimated 2014 visitation total was the highest in Acadia since 1999, park officials have said.

“It was definitely a busy year,” Charlie Jacobi, natural resource specialist for the park, said Monday about 2015. Neither he nor other park officials offered any possible explanation for the increase in visits.

Jacobi told the panel the visitation numbers also reflect an increase in use of the park in autumn over the past 25 years. Numbers for September and October 2015 — 479,000 and 344,000, respectively — are the highest estimates for those months since the park started estimating monthly visitation in 1990.

The previous estimated highs for those months were September 2010, which had about 432,000 visits, and October 2014, which had 314,000, according to National Park Service statistics.

Jacobi told the commission that estimated visitation at the Schoodic section of the park, on the eastern side of Frenchman Bay, increased in 2015 by 39,000 visits, or by 18 percent, since 2013. An electronic traffic counter on the paved road at Schoodic was not working in 2014, he said, which is why that year is not a good reference point.

Jacobi said work vehicles coming and going from the new Schoodic Woods campground, which opened in September 2015, and curiosity among visitors about the new campground may have contributed to last year’s higher visitation estimate for the Schoodic section.

In an effort to come up with more accurate figures, the park changed its methodology for estimating annual visits between 1989 and 1990, which is why the park has annual estimates from the 1980s that are much higher than annual estimates calculated from 1990 onward. The highest-ever annual visitation figure for Acadia is from 1989, when the park came up with an estimate of 5.4 million.

Since then, the highest annual estimate for visits to the park was 2.84 million in 1995.

In other business, Deputy Superintendent Michael Madell told the commission Monday the park expects to start selling park admission passes on its website within the next couple of weeks, which is something Acadia never has done before.

A news reporter in coastal Maine for more than 20 years, Bill Trotter writes about how the Atlantic Ocean and the state's iconic coastline help to shape the lives of coastal Maine residents and visitors....