SIZE

Largest island

The largest island of the United States is Hawaii, at 4,021 sq mi / 10,414 sq km, and still growing slowly. The largest (and longest) island of the lower 48 states is Long Island.

See also the 33 largest islands of the United States.

Lake island

The largest lake island in the United States is Isle Royale, in Lake Superior, Michigan, at 209 sq mi / 541 sq km.

See largest lake islands for the top 20 lake islands in the world.

Volcanic island

The largest volcanic island in the United States is Hawaii, at 4,021 sq mi / 10,414 sq km. Eruptions continue to add to its area.

Freshwater volcanic

Paoha Island in Mono Lake, California, is the largest freshwater volcanic island in the US, at about 3 square miles / 7 sq km.

River island

The largest American river island is Sauvie Island, a 40 sq mi / 104 sq km island in the Columbia River in Oregon.

LOCATION

Remotest island

According to the United Nations’ Environment Programme, the most isolated American island is Nihoa, part of the Hawaiian chain, which is about 200 miles from another island and 3,600 miles from the nearest continent.

Highest island

The highest known islands in the US are in a small lake in southwest Colorado just east of Windom Peak, at 13,100 feet / 3,993 meters.

Lowest island

Southern California’s Salton Sea lies at 227 ft / 69 m below sea level and has a number of islands, notably Mullet Island.

AGE

Youngest volcanic island

The youngest American volcanic island is Fire Island, a small island in the Aleutian chain. It formed in an 1882 eruption.

The youngest major volcanic island is Hawaii, the southernmost of the Hawaiian islands, and thus the most recent to pass over the hotspot that formed the island chain. It is about 800,000 years old.

POPULATION

About 11.5 million Americans are islanders, or about 1 in every 26, inhabiting more than 300 islands. Some 64% of American islanders live on Long Island, New York.

Most populous island

The most populous island in the United States is Long Island, New York, with 7.4 million inhabitants.

Most populous lake island

The most populous American lake island is Mercer Island, in Lake Washington, in greater Seattle. It was home to around 21,710 people as of 2005.

Largest uninhabited

The largest uninhabited American island is Montague Island, Alaska, at 305 square miles / 791 square kilometers. The largest uninhabited island in the lower 48 states is Isle Royale, Lake Superior, which is 209 square miles / 541 sq km.

One million inhabitants

The smallest island on which one million or more people live is Manhattan, in New York City, with 1.48 million inhabitants living in 22 sq mi / 57 sq km (67,000 per sq mi / 26,000 per sq km).

Least densely populated

The least densely populated inhabited American island is Kuiu Island, Alaska, which has 10 inhabitants (as of the 2000 census) sharing 750 sq miles / 1,942 sq km. Each inhabitant thus has 75 sq miles / 194 sq km apiece. This is 5 million times less than the density of Manhattan.

A number of large, inhabited Alaskan islands have less than 20 residents.

One million inhabitants

The smallest island on which one million or more people live is Manhattan, in New York City, with 1.48 million inhabitants living in 22 sq mi / 57 sq km (67,000 per sq mi / 26,000 per sq km).

MISCELLANEOUS

Tallest island

The tallest American island is Hawaii, which rises 13,796 feet / 4,205 meters from sea level to the top of Mauna Kea. It is the second tallest of the world’s islands.

Tallest lake island

Wild Horse Island, in Flathead Lake, Montana, is currently the tallest American lake island, rising 853 feet / 260 meters above lake level.

When the Great Salt Lake is higher than its current level, Utah’s Antelope Island detaches from shore and achieves a height of some 2,396 feet above the lake. Unusually high water levels restore Stansbury Island’s insular status, and make it the highest lake island, at 2,440 feet.

Gregory Butte rises some 951 feet / 290 meters from Lake Powell in Utah, but due to drought it is not currently an island.

Bridges

The largest American island connected to the mainland by a bridge or causeway is Long Island, New York, at 1,401 sq miles / 3,629 sq km.

Most common name

The most common name for islands in the United States is "Big Island”; 140 American islands share that name.

Smallest divided by borders

The smallest island shared by the United States with another country is the west island in Boundary Lake, North Dakota, at about 3 acres / 1.1 ha. It is shared with Canada.

See also islands divided by international borders.

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Contact Joshua Calder at jcalder[at]erols.com with questions or suggestions.

© 1995-2007 Joshua Calder

US island superlatives, island records, biggest island / divided island / highest island / highest population / lake islands / largest American / American geography / geographic superlatives island / largest US island / American geography / geographic superlatives