Ever get that feeling that geography is just a series of trick questions? You think you know the answer, and then—bam—Alaska or Hawaii reminds you how big the world actually is. Most people, if you corner them at a party, will swear up and down that Long Island is the biggest hunk of land surrounded by water in the country.
Honestly? It's not even in the top ten.
If you’re looking for the largest islands in the US, you have to look past the Atlantic. You have to look past the neon lights of Manhattan and the suburban sprawls of New York. To find the heavy hitters, you basically have to head to the Pacific and the rugged, bear-heavy coastlines of the far north.
The Heavyweights: Hawaii and Alaska Battle it Out
It is kind of wild that the top spots are a tug-of-war between tropical volcanoes and subarctic fjords. Hawaii Island—everyone calls it the Big Island for a reason—is the undisputed king. It covers roughly 4,028 square miles. To put that in perspective, it’s about the size of Connecticut.
But here is the kicker: it’s still growing. Because Kilauea and Mauna Loa are active, the island literally gains real estate every time lava hits the sea.
Right on its heels is Kodiak Island in Alaska. Coming in at 3,588 square miles, it’s a massive wilderness where the bears (the famous Kodiak brown bears) outnumber the people in many areas. If you’ve never seen a Kodiak bear, just imagine a grizzly that’s been hitting the gym and eating salmon for breakfast, lunch, and dinner. They are enormous.
The Top 10 List (By the Numbers)
- Hawaii Island (The Big Island), Hawaii: 4,028 sq mi
- Kodiak Island, Alaska: 3,588 sq mi
- Puerto Rico: 3,515 sq mi
- Prince of Wales Island, Alaska: 2,577 sq mi
- Chichagof Island, Alaska: 2,080 sq mi
- St. Lawrence Island, Alaska: 1,983 sq mi
- Admiralty Island, Alaska: 1,646 sq mi
- Nunivak Island, Alaska: 1,625 sq mi
- Unimak Island, Alaska: 1,590 sq mi
- Baranof Island, Alaska: 1,570 sq mi
Wait, where is Long Island? It sits at number 11. It’s about 1,401 square miles. So, while it’s definitely the largest island in the contiguous United States (the lower 48), it’s basically a middleweight compared to the Alaskan giants.
Why Puerto Rico Changes the Conversation
You’ll notice Puerto Rico at number three. Sometimes people forget to include it because it’s a territory and not a state, but geographically, it’s a beast. At 3,515 square miles, it is nearly the same size as Kodiak.
While the Alaskan islands are defined by ice and isolation, Puerto Rico is a dense, vibrant hub of over 3 million people. It’s got the only tropical rainforest in the US National Forest System—El Yunque. It’s also home to mountains like the Cordillera Central, which peaks at over 4,300 feet. It is a massive landmass that offers a completely different vibe than the silent, misty forests of the Alexander Archipelago in Alaska.
📖 Related: Why The Turtle Hospital Marathon FL Is The Best Stop In The Keys
The "ABC" Islands of the North
If you look at the middle of the top ten list, you see names like Chichagof, Baranof, and Admiralty. These are often grouped together as the ABC islands of Alaska.
They are part of the Alexander Archipelago, and they are essentially the world's most beautiful maze of water and wood. Chichagof Island (2,080 sq mi) is famous for having the highest population of bears per square mile of any place on Earth. Seriously, don't forget the bear spray if you're hiking there.
Admiralty Island (1,646 sq mi) is almost entirely protected as a National Monument. The Tlingit people call it "Kootznoowoo," which translates to "Fortress of the Bears." It’s a place where the trees are ancient and the bald eagles are everywhere. It’s rugged. It’s lonely. It’s exactly what people imagine when they think of the "Last Frontier."
The Contiguous US: A Different Story
If we shift gears and talk only about the lower 48, the rankings look totally different. As we mentioned, Long Island takes the crown here. It stretches over 118 miles from New York Harbor out to Montauk Point.
Behind it, you have:
- Padre Island, Texas: 209 sq mi. This is the longest barrier island in the world. It’s basically a giant sandbar that protects the Texas coast.
- Isle Royale, Michigan: 206 sq mi. Tucked away in Lake Superior, this is a backpacker's dream. No cars. No permanent residents. Just moose, wolves, and a lot of hiking.
- Whidbey Island, Washington: 169 sq mi. A key part of the Puget Sound, known for its incredible state parks and naval air station.
Surprising Details and Misconceptions
One thing that trips people up is the definition of an island. Some people argue that Manhattan should be higher on the list of "famous" islands, but in terms of actual land area, it’s tiny—only about 23 square miles. It’s the population density that makes it feel big.
Also, many don't realize how empty some of the largest islands in the US actually are. Take Unimak Island in the Aleutians. It’s the 9th largest at 1,590 square miles, but it has a population of maybe 35 people. It’s dominated by Shishaldin Volcano, one of the most perfectly conical volcanoes on the planet. It’s beautiful, but it’s essentially a giant, smoking rock in the middle of a cold sea.
Real Talk on Visiting These Giants
If you're planning a trip to see these places, your experience will vary wildly.
- The Big Island requires a rental car and a lot of driving. You can go from snow-capped peaks on Mauna Kea to black sand beaches in a single afternoon.
- Kodiak is for the rugged traveler. You’ll likely arrive by ferry or a small plane from Anchorage. It’s about fishing, hunting, and wildlife viewing.
- Puerto Rico is the easiest "big" island to visit for most Americans. No passport required, and you get a mix of Spanish history in Old San Juan and world-class beaches.
Actionable Insights for the Geography Obsessed
If you want to truly appreciate the scale of these places, don't just look at a map. Maps often use projections that shrink the areas near the equator and stretch the areas near the poles.
To get a real sense of the largest islands in the US, use a tool like The True Size Of website. Drag Puerto Rico over to the East Coast, or drop Hawaii on top of a few New England states. You’ll realize that these aren't just "islands"—they are massive, diverse territories that define the edges of the American experience.
Start your journey by exploring the National Park Service websites for Isle Royale or Hawaii Volcanoes. These sites provide real-time updates on trail conditions and volcanic activity, which is pretty vital when the island you're visiting is literally on fire.