The fire that you are asking about is often known as the Bar Harbor Fire after the name of the most important town on Mount Desert Island. The fire occurred in October of 1947, after the end of the tourist season. The long term effect of the fire was to democratize tourism in Bar Harbor.
Before the fire, Bar Harbor was known as a summer destination for very wealthy people. The town had luxurious hotels to cater to such people. It also had an area known as “Millionaires’ Row,” which was a district of “cottages” owned by rich people as summer vacation places. The fire destroyed 67 of these vacation homes as well as five of the hotels.
After the fire, Bar Harbor was never the same as a destination for wealthy people. Instead, motels were built where the luxury hotels and cottages had once stood. Now, it was the middle class that was coming to Bar Harbor on vacation. This was the major change in tourism on Mount Desert Island that came about after the fire of 1947.
Mount Dessert Island is an island off the coast of Maine, is part of the Acadia National Park and also has the distinction of being the second largest island on the Eastern Seaboard.
The island experienced a disastrous fire which started on 17 October, 1947 and could only be completely put out by November 14, 1947. The fire destroyed 17,188 acres of forests, of which over 10,000 acres were part of the Acadia National Park. The great fire also consumed 67 summer estates, five large hotels and 177 year-round homes.
The island was home to middle class and wealthy citizens who owned estates in the "social capital" of the US. The Millionaire's Row contained expensive summer cottages (actually estates, but they were called cottages) that were located on the shore of Frenchman Bay. The fire razed 67 of these impressive cottages. Though loss of life was minimal, the estates were gone forever and were replaced by motels. Similarly, the summer cottages were also gone and it's only the permanent residents who rebuilt their homes.
Thus, the fire caused irreplaceable damage to the estates of the rich (including the Rockfellers, Fords and Carnegies, among others). For the non-resident middle class, the opening up of motels (at the destroyed sites of these estates) meant better lodging while visiting Acadia National Park.