What Are the Biggest Lakes in the U.S.?

In order to keep this relatively simple, we're going to look at largest lakes by surface area.

Some lakes have very deep water, and some are very shallow, which will of course affect how much water the lake holds. In theory, a lake with a small surface but immense depth could be thought of as "bigger" than a shallow lake spread across several square miles.

Therefore, we're going to be looking at surface area exclusively. This makes sense, since when we say "biggest" we generally picture a lake that stretches far and wide, regardless of how deep its waters are. (If you're looking for the deepest lake in the U.S., we've covered that separately.)

Beyond that, the category is open: We'll look at both natural lakes and man-made lakes, as well as freshwater lakes and saline lakes.

It should come as no surprise that the Great Lakes are the largest in the nation. These five lakes are interconnected and found along the border with Canada.

All five lakes are also tremendously valuable to the ecology of the continent, with various plant, bird, mammal and fish species, as well as providing water resources for the surrounding animal and human inhabitants.

Technically, none of these lakes are in entirely within the borders of the United States, but neither are they entirely out of the U.S., so, with a note that we share their glory (and fresh water) with our Canadian neighbors, we'll place them at the top of our list.

1. Lake Superior (31,700 sq mi / 82,000 sq km)

Continuing with our trend of apropos naming, Lake Superior is the largest of the Great Lakes, and the largest lake in the United States.

Bordered by Minnesota, Wisconsin and Michigan — and by Ontario to the north — Lake Superior is also the largest freshwater lake by surface area in the world, a truly impressive distinction.

The massive amount of water that collects in Lake Superior eventually winds its way through the other Great Lakes, finding its way out to the Atlantic Ocean.

2. Lake Huron (23,000 sq mi / 60,000 sq km)

The second-largest lake of the Great Lakes, Huron is bordered by Michigan, with Ontario on the Canada side.

Having 30,000 islands helps it gain an additional superlative: Lake Huron has the longest shoreline of any of the Great Lakes. Its name comes from the name the French colonists knew the Indigenous inhabitants by (they called themselves Wyandot).

3. Lake Michigan (22,300 sq mi / 58,000 sq km)

The third-largest of the Great Lakes (and also the third largest lake in America) is Lake Michigan. Technically, due to being connected by the Straits of Mackinac and having the same surface elevation as Lake Huron, these two can be considered the same lake.

This nifty bit of trivia means that, in the hydrological sense, Lake Michigan-Huron, as they are sometimes called, constitute the largest freshwater lake in the world by surface area.

4. Lake Erie (9,910 sq mi / 25,700 sq km)

The fourth-largest Great Lake is Lake Erie. Situated off the lake's northern shore is Ontario; to the south are the states Michigan, Ohio, Pennsylvania and New York. It's the southernmost of the Great Lakes.

The Erie canal, named for the lake, connected Lake Erie to the Hudson River, which significantly altered trade in North America. It also led to the introduction of invasive species, which had negative effects on native species such as the lake trout.

5. Lake Ontario (7,340 sq mi / 19,000 sq km)

The fifth of the Great Lakes, in terms of surface area, is Lake Ontario. It is also the furthest east of the Great Lakes, and the last great lake that the water flows through on its way out to the Atlantic Ocean, via the Saint Lawrence River.

With Canada to the north and New York State to the south, the U.S.-Canada border goes right down the middle of the lake.

Lake Ontario gets its name from the Wyandot language, in which it means — for real — "great lake." Like all the lakes in the Great Lakes system, it was formed in the last ice age, 14,000 years ago.

While human beings have shown an impressive ability to shape nature, nothing we've created can really hold a candle to the natural wonders that are the Great Lakes. Still, in the damming of rivers and lakes, we've created some pretty impressive bodies of water.

Below is a list of the five biggest human-made lakes in the United States. Note that a "reservoir" is technically a lake that has been dammed, adding to an increase in surface area and volume. It's possible to create a lake from scratch, but much more rare and unlikely to be very big.

1. Lake Oahe (578 sq mi / 1,500 sq km)

Located in North and South Dakota, Lake Oahe is the largest man made lake in the United States. Formed by the Oahe dam, it holds back a portion of the Missouri river, creating a massive store of fresh water.

2. Lake Sakakawea (575 sq mi / 1,489 sq km)

Also found in the Missouri basin, Lake Sakakawea was formed by the creation of the Garrison Dam in North Dakota. The dam was built in the 1950s by the U.S. Army Corps of Engineers.

3. Red Lake (444 sq mi / 1,250 sq km)

Red Lake is found in the state of Minnesota. Known as a popular ice fishing spot, it provides native habitats for fish species such as the bluegill, lake sturgeon and yellow perch.

4. Fort Peck Lake (383 sq mi / 992 sq km)

Located in Montana, Fort Peck Lake is formed by the Fort Peck reservoir on the Missouri River. Home to the Charles M. Russell National Wildlife Refuge, it is a tourist attraction and a popular destination for many bird species.

5. Truman Lake (327 sq mi / 847 sq km)

Found in Missouri, Truman Lake is the fifth-largest man made lake in the United States. Unlike some reservoirs, which are used to store drinking water, Truman Lake is primarily a means of flood control, with recreation and hydroelectric power generation as additional purposes.

There are a whole lot of lakes in the United States, as should be evident by now. In fact, every state in the union has lakes, and here is a list of the biggest in each state. Once again, we're going to measure their size in terms of surface area. It's worth noting that many of these lakes are human-made.