Measuring 14 kilometres (9 miles) long and about 5 km (3 miles) wide, it has an area of 39.6 km² (15.3 sq mi). In addition to the Lubec bridge, the island is accessible in the summer months by an automobile ferry from nearby Deer Island and from there via another ferry to mainland New Brunswick. The island's permanent population in 2001 was 1,195. The majority of residents are employed in the fishing/aquaculture or tourism industries.
The island was originally settled by the Passamaquoddy Nation who called it Ebaghuit.
The first Europeans were reportedly from the French expedition of Pierre Dugua de Monts (Sieur de Monts) and Samuel de Champlain who founded the nearby St. Croix Island settlement in 1604. France named the island Port aux Coquilles ("Shell Harbour"). Following the War of the Spanish Succession, under terms of the Treaty of Utrecht (1713), the island came under British control and was placed in the colony of Nova Scotia, having ceased to be included in the French colony of l'Acadie.
In 1770, a grant of the island was made to Captain William Owen (1737-1778) of the Royal Navy who renamed it Campobello. The island's name was derived from Britain's Governor of Nova Scotia, Lord William Campbell, and was mixed with "bello" from the French, Spanish and Italian origins of the word "beautiful". The creation of the colony of New Brunswick in 1784 saw the island transferred to the new jurisdiction and by the end of the 18th century, the small island had a thriving community and economy, partly aided by Loyalist refugees fleeing the American Revolutionary War. Smuggling was a major part of the island's prosperity after the Revolution, a custom largely winked at by local officials. During the War of 1812 the British Royal Navy seized coastal lands of Maine as far south as the Penobscot River but returned them following the war, except for offshore islands. In 1817 the U.S. relinquished its claim for the Fundy Isles (Campobello, Deer, and Grand Manan Islands) and the British returned islands in Cobscook Bay including Moose Island but notably did not return Machias Seal Island. By the mid 19th century Campobello Island had a population in excess of 1,000. In 1910 1230 people lived there.
In 1866, a band of 700+ members of the Fenian Brotherhood arrived at the Maine shore opposite the island with the intention of seizing Campobello from the British. The US government intervened and a military force dispersed the Fenians. This action served to reinforce the idea of protection for New Brunswick by joining with the British North American colonies of Nova Scotia, Canada East, and Canada West in Confederation to form the Dominion of Canada.
Included in this group was Sara Delano and her husband James Roosevelt Sr. from New York. Sara Delano had a number of Delano cousins living in Maine and Campobello offered a beautiful summer retreat where their family-members could easily visit. From 1883 onward, the Roosevelt family made Campobello Island their summer home. Their son, Franklin D. Roosevelt, President of the United States, would spend his summers on Campobello from the age of one until, as an adult, he acquired a larger property - a 34 room "cottage" - which he would use as a summer retreat until 1939. It was here that Franklin D. Roosevelt, Jr., was born in August of 1914. It was at Campobello, in August 1921, that Roosevelt fell ill with polio. It is believed that he contracted it at Bear Mountain, New York, at a boy scout camp. The virus can take up to 30 days to hit, and he was only on Campobello for about 10 hours when he fell ill with polio, an illness which resulted in his total and permanent paralysis from the waist down. Roosevelt did strive for seven years to try to gain reuse of his legs but never did walk unassisted. He spent most of his time after polio in Warm Springs, Georgia.
During the 20th century, the island's prosperity from its wealthy visitors declined with the change in lifestyles brought on by a new mobility from automobiles, airplanes, and air conditioning in large inland cities. Nonetheless, for President Roosevelt, the tranquility was exactly what he and his family cherished and the property remained in their hands until 1952 when it was sold by Elliot Roosevelt (Franklin and Eleanor's 4th child.) Elliot decided to sell the house after his mother, Eleanor had sold it to him. Elliot sold it to the Hammour Brother's of Boston and they owned it up until 1952 however they said Eleanor was always welcome to come whenever she pleased. In 1952 the brother's tried to sell it but got no takers, they then decided to donate the cottage to both America and Canada. The Roosevelt Campobello International Park is the only one of its kind because it is run by both Canadian and American governments but is built on Canadian soil. The park is now equally staffed with both American and Canadian employees.
The Franklin Delano Roosevelt Bridge, which connects the island to the U.S. mainland at Lubec, was built in 1962 and brought a tourism revival, particularly after the 11 km² (2,800 acre) Roosevelt Campobello International Park was created in 1964. The park was officially opened by U.S. President Lyndon Johnson and Canadian Prime Minister Lester Pearson when the two met in Canada in 1966.
In 1960, motion-picture producer Dore Schary and director Vincent J. Donehue made the film Sunrise at Campobello, based on Schary's Tony Award winning Broadway play of the same name. Starring Ralph Bellamy as Franklin D. Roosevelt, the film covered the years 1921 to 1924 at Campobello Island and events leading up to Roosevelt's nomination as the Democratic Party's candidate for President.