One day in 1898, Olof Ohman was just about to cut down a poplar tree on his land in Kensington, Minnesota, when he noticed a big, flat stone, carved with script he didn't recognize.

Ohman called on his neighbor, Nils. The two of them started digging in hopes the stone might mark buried Native American treasure.

In fact, they'd discovered a different kind of treasure: proof that Vikings had come to Minnesota — 130 years before Columbus left Spain. The inscription told of the Norsemen's short stint in this land. One day some of them went fishing. When they returned, they found 10 of their fellow marauders dead, massacred by the natives.

Within a year, what had come to be called the Kensington Runestone was declared a hoax. Among other problems, its inscription used umlauts. Those little markings above Swedish-language letters were not used in carvings the Vikings left behind. They would, however, have been second nature to a guy who moved from Sweden to Minnesota in 1881.

Just why Ohman would have scammed his fellow Minnesotans was a mystery. He certainly didn't do it to get rich. Ohman eventually sold his "artifact" to the Minnesota Historical Society for all of $10.

By that time, the story was out of his hands. Myths, like rivers, tend to carve their own paths. Big lies give meaning to the small truth of our lives.

So it was that Minnesotans made use of Olof Ohman's mythical runestone. It gave roots to European immigrants who found themselves in a strange land. And the story of an American Indian-led massacre made some feel better about the white man's appalling slaughters of natives a generation earlier.

Hjalmar Holand, a Norwegian-born Wisconsinite who got his start as a traveling book salesman, spent decades trying to prove the stone's authenticity. Holand traveled the Midwest documenting big rocks with holes in them: mooring stations, Holand theorized, where the Vikings would have anchored their ships.

Meanwhile, John Ireland, the immigrant Archbishop of the St. Paul Diocese, pointed to the stone's religious invocation — "Ave Maria, save from evil," reads the stone's last line — as evidence that the Scandinavians who predated Columbus were Catholics. He and other church leaders used the stone to convert Minnesotans of Nordic heritage back into the fold.

It worked well enough. There's an 8:30 a.m. mass every Sunday morning at Our Lady of the Runestone church in Kensington.

The stone itself moved on to nearby Alexandria, where it's housed in a museum that places it alongside foundational Minnesota bloodlettings like the U.S.-Dakota War and the Civil War. But the stone's pull would wane.

"I didn't think about it a lot growing up," says historian David M. Krueger, who grew up in Alexandria. "It had kind of grown out of fashion by the 1970s and '80s."

It's now making a comeback. A number of amateur historians and boosters have circled back to reargue its case. In 2009, around the time it ran out of actual history to sell, the History Channel aired a documentary called Holy Grail in America. Relying heavily on the research of forensic geologist Scott Wolter, a Chanhassen native, the show suggested the stone was evidence that the last of the Knights Templar had relocated to central Minnesota.

Wolter parlayed his performance into a full-fledged series called America Unearthed. In a subsequent episode, he explored the possibility that a Minnesota farmer's discovery of the bones of a "giant" might be yet more proof that Vikings had made it here.

The Kensington Runestone even has its own website, which explains that, despite 100 years of scurrilous attacks against it, the tablet has "recently proven to be authentic," inspiring a "major rewrite of American history."

That the myth lives on, and is only gaining in strength, tells us a lot more about modern Americans than marooned 14th-century Vikings. There has always existed a peculiar and distinctively American anti-intellectual populism. We are not so easily convinced by geeky experts.

Krueger, who has since written a book about the stone's continuing hold on Minnesota's imagination, is confused about why there is such interest in finding a thread to a white America before Columbus. (Consider the Mormons, who believe that Jesus Christ got here 1,300 years before Ohman's Vikings did.)

"There is a power to myth, and historians talk about creating a usable past," Krueger says. "It's helpful. But it's disturbing that, on one level, Americans are only interested in pre-Columbian North American history if white people are involved."

If we learned more about the non-white pre-Columbus days, what would we find? More myths. The Ojibwe tell the story of Nanabozho, forced to start civilization anew after he was the sole survivor of a great flood. Sound familiar?

The best interpretation of the Kensington Runestone came from the late historian Russell Fridley, longtime leader of the state historical society. It's not even a hoax, Fridley said, but a "monument to Scandinavian frontier humor."

Olof Ohman lived another 40 years after discovering the stone, and never once changed his story. If it really was a joke, he's the only one who got it.