When most people picture the United States, they imagine one big stretch of land from the Atlantic to the Pacific, bordered by Canada to the north and Mexico to the south. It is a fair picture, but it leaves out a huge part of the country. So, how many islands does the USA have? The answer surprises almost everyone who hears it: the United States has more than 18,000 named islands, spread across every region of the country, from the icy waters of Alaska to the tropical shores of Hawaii and the busy harbors of the East Coast. America is far more of an island nation than most people ever realize.
Islands are part of the American story in ways that go far beyond beaches and vacations. They hold military bases, national parks, historic lighthouses, fishing towns, and entire communities that can only be reached by boat or plane. Some islands are home to millions of people. Others are home to no one at all except seabirds and seals. In this guide, we break down the real numbers, explain where the islands are, and look at the most famous ones you can actually visit.
How Many Islands Does the USA Have?
The short answer is that the United States has more than 18,000 named islands. The most commonly cited figure comes from the United States Geological Survey, which counts about 18,617 named islands in the country. That number only includes islands with an official name recorded in the Geographic Names Information System. The true total, including tiny unnamed islets and rocks that appear at low tide, is certainly higher, but no official count covers every single one.
Why is there no exact number? Counting islands is harder than it sounds. A rocky outcrop might be an island at low tide and disappear under water at high tide. A small sandbar might exist one year and wash away the next. Rivers create new islands when they change course, and coastal erosion can split one island into two. The 18,617 figure is the best official answer we have, and it is the number most geography sources use. So when someone asks how many islands does the USA have, the honest, verifiable answer is: at least 18,617 named islands, and probably many more unnamed ones.
To put that in perspective, that is more islands than many countries have in total. The islands range in size from huge landmasses like Long Island in New York and Kodiak Island in Alaska, which are bigger than some countries, down to tiny specks of rock off the coast of Maine that barely fit a single tree. Together, they add an enormous amount of coastline to the United States, and they shape the way Americans fish, trade, travel, and defend the country.
The USGS Count: About 18,617 Named Islands
The United States Geological Survey, known as the USGS, keeps the official record of geographic names in America. Its Geographic Names Information System lists every island that has been given an official name, and that list runs to about 18,617 entries. This count includes islands in all 50 states, plus islands in U.S. territories such as Puerto Rico, Guam, and the U.S. Virgin Islands.
It is worth understanding what this count does and does not include. It counts islands in lakes and rivers as well as in the ocean. The Great Lakes alone contain hundreds of named islands, including Isle Royale in Michigan, a wilderness national park that is the largest island in Lake Superior. Rivers like the Mississippi, the Ohio, and the Columbia are dotted with islands, many of which have names and small communities or farms on them. The USGS count also includes barrier islands, the long, thin strips of sand that protect much of the Atlantic and Gulf coasts from storms.
What the count does not include is just as interesting. It leaves out the countless unnamed islets, rocks, and sandbars that appear on nautical charts but never received an official name. In Alaska alone, where the coastline is enormous and much of it is remote, there are thousands of small islands and rocks that have never been formally named. The real number of American islands, named and unnamed, is therefore certainly well above 18,617.
Alaska: The State With the Most Islands
If you want to know which state has the most islands, the answer is Alaska, and it is not even close. Alaska has more than 2,600 named islands, and many experts believe the real total, including unnamed ones, is far higher. Alaska’s coastline stretches for more than 6,600 miles, longer than the entire coastline of the rest of the United States combined, and much of that coastline is broken into islands, fjords, and channels.
The most famous island group in Alaska is the Aleutian Islands, a chain of more than 300 islands that sweeps westward from the Alaska Peninsula toward Russia. The Aleutians are volcanic, windswept, and remote, and they played an important role in World War II, when Japanese forces occupied two of them, Attu and Kiska. Today, the Aleutians are home to fishing communities, wildlife refuges, and some of the richest fishing grounds in the world.
Alaska’s largest island is Kodiak Island, the second-largest island in the United States after the island of Hawaii. Kodiak is famous for its giant brown bears, which are among the largest land predators on Earth, and for its fishing industry. The island is about 3,600 square miles in size, and its main town, also called Kodiak, is one of the busiest fishing ports in the country. Other major Alaskan islands include Prince of Wales Island, Chichagof Island, Admiralty Island, and Baranof Island, all part of the Alexander Archipelago in the southeast of the state. Admiralty Island is sometimes called the Fortress of the Bears because it has one of the highest densities of brown bears anywhere in the world.
For travelers, Alaska’s islands offer some of the wildest scenery in America: misty fjords, glaciers calving into the sea, whales, sea otters, and puffins. Many of the islands are only reachable by ferry or small plane, which keeps them quiet and unspoiled. If you are planning a trip, the Alaska Marine Highway ferry system is the best way to hop between island communities, and it is an adventure in itself.
Hawaii: 137 Islands, 8 Main Ones
Hawaii is the only U.S. state made up entirely of islands, and it is the state most people think of first when they ask how many islands does the USA have. The Hawaiian archipelago has 137 islands in total, but only 8 of them are considered the main islands, and only 6 of those are open to visitors.
The eight main Hawaiian islands are Hawaii (often called the Big Island), Maui, Oahu, Kauai, Molokai, Lanai, Niihau, and Kahoolawe. The Big Island is the largest island in the entire United States, bigger than all the other Hawaiian islands combined, and it is still growing, thanks to the active volcano Kilauea, which has been adding new land for decades. Oahu is the most populated island and home to Honolulu, Waikiki Beach, and Pearl Harbor. Maui is famous for the road to Hana and the sunrise at Haleakala. Kauai, the Garden Isle, is known for its green cliffs and the dramatic Na Pali Coast.
The other 129 islands in the chain are mostly small, uninhabited islets, many of them part of the Papahanaumokuakea Marine National Monument, one of the largest marine protected areas in the world. These Northwestern Hawaiian Islands stretch for more than 1,200 miles beyond the main islands and are home to endangered monk seals, green sea turtles, and millions of seabirds. Niihau, the Forbidden Isle, is privately owned and closed to most visitors, while Kahoolawe is uninhabited and used for cultural and environmental restoration after decades as a military training ground.
Hawaii became the 50th state in 1959, and its island identity shapes everything about it, from its food and music to its politics and economy. Tourism is the biggest industry, but the islands also host major military bases, astronomy observatories on the summit of Mauna Kea, and farms growing coffee, macadamia nuts, and pineapples.
Islands in the Lower 48 States
Most of America’s islands are not in Alaska or Hawaii. The lower 48 states have thousands of islands of their own, and many of them are places Americans know well, even if they do not think of them as islands.
- Long Island, New York: The largest island in the contiguous United States, home to nearly 8 million people across Brooklyn, Queens, Nassau, and Suffolk counties. It stretches about 118 miles from New York City to Montauk Point.
- Florida Keys: A chain of about 1,700 islands curving southwest from the Florida mainland, connected by the Overseas Highway. Key West, the southernmost point in the continental United States, is the most famous of them.
- San Juan Islands, Washington: More than 170 named islands in the Salish Sea near Seattle, known for orca whales, kayaking, and small artsy towns like Friday Harbor.
- Islands of Maine: Maine has more than 3,000 islands along its jagged coast, including Mount Desert Island, home to Acadia National Park, one of the most visited national parks in America. For more on the country’s protected places, see our guide to how many national parks the USA has.
- Channel Islands, California: Eight islands off the Southern California coast, five of which make up Channel Islands National Park, sometimes called the Galapagos of North America.
- Great Lakes islands: The Great Lakes hold hundreds of islands, including Isle Royale, the Apostle Islands in Wisconsin, and the Thousand Islands region of the St. Lawrence River, where New York meets Canada.
- Barrier islands: The Outer Banks of North Carolina, Padre Island in Texas, and the islands along the Gulf Coast protect the mainland from hurricanes and provide beach towns, wildlife refuges, and fishing villages.
Many of these islands are easy to visit by car, ferry, or a short flight, and they make excellent weekend trips. The Outer Banks, the Florida Keys, and the San Juan Islands are all popular summer destinations, while islands like Mackinac Island in Michigan, where cars are banned and everyone travels by horse or bicycle, feel like a step back in time.
U.S. Territories and Their Islands
The island count grows even larger when you include U.S. territories, which are not states but are under American sovereignty. Puerto Rico is the largest of these, an island of about 3.5 million people in the Caribbean, with its own smaller islands, Vieques and Culebra, which are famous for their beaches and bioluminescent bays. Guam, in the western Pacific, is a strategic military outpost and a popular tourist destination for visitors from Asia. The U.S. Virgin Islands, St. Thomas, St. John, and St. Croix, are another Caribbean territory, and St. John is home to Virgin Islands National Park, which covers about two-thirds of the island.
American Samoa, in the South Pacific, is made up of five main islands and two coral atolls, and it is home to the National Park of American Samoa, the only U.S. national park south of the equator. The Northern Mariana Islands, a commonwealth in the Pacific, include Saipan, Tinian, and Rota, islands with deep World War II history. The United States also controls several small, mostly uninhabited islands, including Midway Atoll, famous for the Battle of Midway, and Wake Island, a remote airfield in the Pacific.
People born in most U.S. territories are U.S. citizens, with the exception of American Samoa, where residents are U.S. nationals. Territories send delegates to Congress but do not have voting representation, and they do not vote in presidential elections. Their island status shapes their economies, which rely heavily on tourism, military spending, and shipping.
Famous American Islands Worth Visiting
With more than 18,000 islands to choose from, picking favorites is hard, but a few stand out for history, beauty, and adventure. Alcatraz Island in San Francisco Bay was once the most famous federal prison in America, home to gangsters like Al Capone, and today it is one of the most visited historic sites in the country. Ellis Island in New York Harbor was the gateway for more than 12 million immigrants between 1892 and 1954, and its museum tells the story of how America was built by newcomers.
Other islands worth a visit include Catalina Island off Los Angeles, a resort island with clear water, bison, and a famous casino building; Nantucket and Martha’s Vineyard off Massachusetts, classic New England summer escapes with lighthouses and whaling history; and the Dry Tortugas, a cluster of tiny islands 70 miles west of Key West, home to a massive 19th-century fort and some of the best snorkeling in the country. Each of these islands has its own character, and together they show how varied American island life can be.
If you are curious about how the country is divided on land, our article on how many counties the USA has is a good companion read. And for the story behind the flag that flies over all of these islands, see the history of the U.S. flag.
How Many Islands Does the USA Have in Total?
So, how many islands does the USA have in total? The best official answer remains about 18,617 named islands, a figure that covers the 50 states and the territories. The real total, counting every unnamed rock and islet, is certainly higher, and it changes slowly over time as erosion, volcanic activity, and rising sea levels reshape the coastline. What the number really tells us is that America is an island nation in a way most people never stop to consider.
Islands give the United States its longest coastlines, its richest fishing grounds, its most strategic military positions, and some of its most beloved vacation spots. They hold the history of immigration at Ellis Island, the wildness of Kodiak’s bears, the volcanoes of Hawaii, and the quiet of Maine’s offshore villages. Whether you live on one, visit one, or simply admire one from the mainland, America’s islands are a huge and fascinating part of the country.
Ready to explore them for yourself? Start with the islands closest to you, then work your way toward the big ones: Hawaii, the Florida Keys, the Outer Banks, and Alaska’s Inside Passage. Share this guide with a friend who loves travel, and tell us in the comments which American island is your favorite, or which one is next on your list. The United States has more than 18,000 islands waiting, so there is always another one to discover.