Largest Land Mammals in the US
Between the Great Plains, the Rocky Mountains, and the vast wilderness of Alaska, the U.S. hosts some massive animals. Here are the ten heaviest land mammals found within U.S. borders, ranked by maximum recorded weight.
1. American Bison
Max weight: ~2,000–2,100 lbs
The largest land mammal in the U.S., and the country’s official national mammal. Bulls are stocky, humped giants covered in shaggy brown fur, once numbering in the tens of millions across the Great Plains before being hunted to near-extinction. Today they survive mainly in protected herds like the one in Yellowstone, with a small reintroduced wood bison population — the heaviest bison subspecies — in Alaska.
2. Moose
Max weight: ~1,500–1,800 lbs
The largest member of the deer family, moose are unmistakable with their long legs, bulbous snouts, and palmate antlers. Alaska is home to the Alaska-Yukon subspecies, the biggest moose in the world. Despite their bulk, moose are strong swimmers and surprisingly fast runners.
3. Polar Bear
Max weight: ~1,500–1,700 lbs (record over 2,200 lbs)
The largest land carnivore on Earth, found along Alaska’s Arctic coast. Polar bears are built for sea ice, with black skin, water-repellent fur, and a thick layer of blubber. They hunt seals from the ice, which makes them especially vulnerable to a warming climate.
4. Kodiak Bear
Max weight: up to ~1,500 lbs
A subspecies of brown bear found only on Alaska’s Kodiak Archipelago, the Kodiak bear is the largest bear in the U.S. after the polar bear. Isolated on their islands with abundant salmon runs, they’ve grown to enormous size compared to mainland brown bears.
5. Grizzly Bear
Max weight: up to ~1,200 lbs (coastal populations)
The mainland cousin of the Kodiak, grizzlies range from the Rockies up through Alaska. Coastal grizzlies in Alaska, with access to rich salmon runs, tend to grow considerably larger than their interior relatives in places like Yellowstone and Glacier National Park.
6. Elk (Wapiti)
Max weight: up to ~1,200 lbs
American elk are the largest wapiti subspecies in the world, and the Roosevelt elk of the Pacific Northwest rainforests are the biggest of all. Bulls grow impressive branching antlers each year and are known for their eerie, far-carrying bugle calls during the fall rut.
7. Wild Horse
Max weight: up to ~1,000 lbs
Feral mustangs, descended from horses brought by Spanish colonists, roam free-ranging herds across the American West — including well-known populations in Nevada, Wyoming, and on barrier islands like Assateague.
8. Muskox
Max weight: up to ~900 lbs
An Arctic specialist reintroduced to Alaska after being hunted out in the 1800s, the muskox has a shaggy double coat built to withstand brutal cold. It’s more closely related to goats and sheep than to oxen, and when threatened, muskoxen famously form a defensive circle with the young at the center.
9. American Black Bear
Max weight: up to ~880 lbs
The most widespread and numerous bear species in the U.S., found in 40+ states. While much smaller on average than grizzlies or polar bears, black bears in food-rich regions like the Appalachians can still reach surprising sizes — one boar killed in North Carolina weighed 880 lbs.
10. Caribou (Reindeer)
Max weight: up to ~700 lbs
Caribou close out the list, found only in Alaska among U.S. states. They’re known for having the longest land migration of any mammal in North America — some herds travel over 1,000 miles a year between calving grounds and winter range — and are the only deer species in which both males and females grow antlers.
