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For more than a century, Minnesota has made its abundance of lakes a signature part of its identity: the Land of 10,000 Lakes. But our neighbors to the east claim to have us beat.

Wisconsin’s Department of Natural Resources touts that the state has “more than 15,000 lakes.” In an apples-to-apples lake battle, however, Minnesota is the clear winner. That’s because many of the “lakes” in Wisconsin’s tally would be considered ponds in Minnesota. Officials in the two states follow very different standards.

This discrepancy fuels plenty of jokes and trash-talk between the two states.

“Sometimes I take a leak out behind my garage and it forms a puddle,” a commenter wrote on a 2023 Reddit thread on this topic. “If I was in Wisconsin I could call it a lake.”

A reader wondered why the two states have such different metrics for defining what counts as a lake. They sought answers from Curious Minnesota, the Star Tribune’s reader-generated reporting project.

Similar lake battles are actually being waged around the world. The reason? There is no “universal, scientifically based” definition to differentiate ponds from lakes and wetlands, according to a 2022 article in the journal Scientific Reports. This glaring absence “hampers science, policy, and management, and creates confusion,” the authors wrote.

Minnesota defines a lake as a body of water with an area of at least 10 acres. That approach makes more sense than Wisconsin’s less precise definition, said John Downing, a professor of biology at the University of Minnesota Duluth and director of the water science research program Minnesota Sea Grant.

But he said the number that’s emblazoned on Minnesota license plates, 10,000, is off by a wide margin. The actual number is just over 14,000, by Downing’s estimation.

Becoming the Land of 10,000 Lakes

The state’s unofficial slogan has origins dating at least as far back as 1874, when a professor named Ransom Humiston gave a speech at the State Fair about Minnesota’s “glorious future.” Humiston co-founded the settlement that became Worthington, Minn.

“We may justly claim that we are the HUB of North America … we have thirty-eight rivers in the State, six of which are navigable within the State, amounting to an aggregate of about 1,200 miles,” said Humiston, according to a write-up in the Worthington Advance. “Then come over 10,000 lakes, abounding in delicious fish, and the paradise of myriads of waterfowl.”

Another state nickname nearly prevailed, however. At the Pan-American Exposition in Buffalo, N.Y., in 1901, Minnesota advertised itself as the “Bread and Butter State.”

A turning point came in 1917, when state boosters went all-in on the “10,000 Lakes” idea in hopes of capitalizing on the growing popularity of automobile tourism. “Ten thousand Minnesota lakes are calling you,” proclaimed newspaper ads in places like Kansas City. “Come up and play where it’s springtime all the summer long.”

A resort owner and state senator from Walker soon created a group called the Ten Thousand Lakes of Minnesota Association to market the state as a tourist destination. More than 50 communities contributed funds.

“Tourists have seen Colorado and the Yellowstone park and are looking for new fields to explore,” the Austin Daily Herald reported in 1918. “No state in the union has more natural beauty than Minnesota with its 10,000 lakes.”

The phrase landed on state license plates in 1950 and has been there ever since.

All things considered, Humiston’s 1874 estimate wasn’t too shabby. But today, Downing is able to get an accurate count by analyzing the Minnesota DNR’s database of waterbodies and tallying everything that’s 10 acres or larger.

That’s how he landed on 14,380.

Why 10 acres?

The 10-acre cutoff helps delineate the character of a lake versus its more mucky cousin, the pond. Lake scientists believe that a lake is only a lake if it has a “wave-swept shore,” Downing said.

“Having waves is important, because it changes the character of the water body,” he said. “It changes the character of how the shorelines work and how the sediment builds up.”

Here’s how he does the math: Winds of about 35 miles an hour need to blow across a certain distance of surface water in order to form waves of about 4 inches. Assuming that the body of water is roundish, it would need to be about 10 acres to get the right-sized waves, he said.

If a body of water is too small to have waves, its shores are usually “marshy, full of organic material and mucky stuff,” he said.

Although limnologists (scientists who study lakes) generally agree on this definition, there’s no federal standard to separate lakes from ponds. The U.S. Geological Survey even lumped them into one category in its National Hydrography Dataset.

So in each of the 50 states, the department of natural resources is free to draw the line between lake and pond as they wish. When tallying their 15,000 total, Wisconsin’s agency includes “lakes” as small as 2.2 acres. This is a definition that even Cory McDonald, a research scientist with Wisconsin’s DNR, has called “somewhat nonconventional.”

In 2019, the fact-checking site Politifact analyzed the national data in a definitive takedown of comments by Wisconsin’s lake-touting tourism secretary, Sara Meaney.

Meaney had claimed on the radio that her state had more lakes than Minnesota, saying, “We win. We win.” But when PolitiFact limited lakes using the 10-acre standard, Wisconsin’s count dropped from 15,000 to 6,176.

Quibblers sometimes point out that Minnesota is larger than Wisconsin, opening up a different battle over lake density.

That’s getting a little too in the weeds for Downing’s taste. Both states are truly lake-rich, he said.

“Northern Wisconsin and northern Minnesota are among the more what we call lacustrine places in the world,” he said. “That means ‘lakey,’ and it changes how the forests work and alters weather. It is a huge tourist and economic engine.”

“We are the water states, really, of the United States,” he said. “It really does distinguish our states from others.”

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