The building of private cottages began about in 1880, historians say.
Transportation was the key to delivering newcomers. The horsecar line ran until 1895 when it was replaced by an electric railway in 1897. A private road from Rolfes Lane to the island was made public in 1906.
The trolleys ran until about 1922, when the tracks were taken up and rail service was replaced by buses and private autos. When middle-class families began owning cars, the island became a major destination on the North Shore.
But catastrophe could occur on land as well as on the sea. In 1914 the Plum Island Hotel burned down, and in 1933 the Pavilion also was destroyed by fire.
But development continued. Construction on a macadam road now called Northern Boulevard began in 1920. Cottages evolved into year-round homes, as middle-class families began building small residences.
The island was also discovered by emerging naturalists. In 1929, a philanthropist named Annie Hamilton Brown of Stoneham left money in her will to the Federation of Bird Clubs of New England for a wildlife sanctuary on the south end of the island.
By the mid-1930s, almost 1,500 acres had been acquired by the federation, which merged with the Massachusetts Audubon Society.
In 1942, the sanctuary land was turned over to the federal government. A summer camp known as Camp Sea Haven for polio patients and others was operated for several decades through the ’80s, but that facility, as many others, has slipped into history.
Today the southerly, “pristine” end of the Island is known as the Parker River National Wildlife Refuge. Each year it draws thousands of birders and nature lovers. Among its well-known inhabitants are the nasty greenhead fly and the lovable piping plovers.
In recent years, the increasing population on the north end of the island has raised concerns about water quality. State health officials within the last decade have directed local leaders to develop a new water and sewer system to the island.