But that was a different time, Mr. Barter said as we walked past the vestiges of an acre-wide saltwater swimming pool Dorr built. “The man was like a beaver,” he said. “Constantly building.” Like a bona fide visionary, the father of Acadia died blind and penniless, having invested all of his resources in the park. World War II, the Bar Harbor, Me., fire of 1947 and the arrival of auto touring all but ended hiking in Acadia for 30 years. By 1960, almost half of the park’s trails were decommissioned.

For decades, a small cult of hikers mapped and walked the lost trails of Acadia, scouring the softwood for clearings, a cairn or granite steps covered in moss. Nature takes quickly, and many were completely lost. But grant money rebuilds even faster, and in 1998, a local organization called Friends of Acadia saved the trail system with the Acadia Trails Forever campaign, which raised $9 million in private donations to go with $4 million in park entry fees. This initiated the rehabilitation of the trails.

Since then Acadia’s trail crew, in collaboration with the Olmsted Center for Landscape Preservation, has restored miles of lost trails like the smooth, graded path Mr. Barter led me to a few minutes later.

The Schooner Head Trail was another Dorr-original, built in 1901 and designed to meander three and a half miles through fir and spruce forests to 100-foot sea cliffs south of Bar Harbor. It was a classic Acadian “broad path,” wide enough to walk arm-in-arm and topped with crushed stone so the gentry could wear dress shoes. The trail was closed in the 1950s because of a lack of use and maintenance. When Mr. Barter and his crew started restoring it in 2008, there were trees as thick as telephone poles growing in the middle of it. The fix was 14,000 hours of labor, 1,500 tons of blown ledge, 500 tons of crushed rock, 100 culverts and 3 miles of ditches dug by hand. And just like that, one of the lost trails of Acadia was revived.

Image George Dorr, a founder of Acadia National Park, taking in the view of Mount Desert Island. Credit... The National Park Service at Acadia National Park

It takes a special kind of person to spend the summer digging ditches and hauling 200-pound granite blocks through the woods. The original path-makers were inspired by a pioneering spirit and a sense of philanthropy, perhaps something only a wildly successful industrialist can feel. Today’s trail crew, Mr. Barter said, is a different demographic, but their inspiration is much the same.