Historians have long wondered when the historic McGulpin House on Mackinac Island was built. The answer was in the tree rings.

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For more than two centuries, the homely little house that sits at Market and Fort streets on Mackinac Island has held its secrets tight to its ancient timbers. Certainly, historians could date it to the 18th century given its French Canadian-style construction typical to that era—squared horizontal pine logs and a steeply pitched roof covered in cedar bark that naturally sheds rain and snow. But when exactly was it built? Date the house (now known as the McGulpin House and managed by Mackinac State Historic Parks) precisely and you’d have an intimate window into Mackinac Island in the 1700s. And what a dramatic and colorful century that was in the Straits of Mackinac—the confluence of lakes Michigan and Huron—where the island is located. The stately Victorian cottages with their verandas and rocking chairs that Mackinac Island is now known for came later. Way back then, the Straits was a wild frontier where Native Americans, the French, British and finally Americans warred over possession of what was then the hub of the lucrative Great Lakes fur trade.

For decades historians postulated that the home could have been built as far back as 1740. If that was the case, it would have been built across the Straits at Fort Michilimackinac most likely by Frenchmen as the Straits were controlled by France then. And how would it have gotten to the island? The British (they took control of the Straits in 1780) could have brought it across the ice along with most of Fort Michilimackinac as a defensive move at the end of the Revolutionary War. “There was some suggestion that it may have been associated with the Church of Ste. Anne, which got moved over in about 1780,” says Craig Wilson, chief curator of Mackinac Island State Historic Parks. Or was the McGulpin House built later, after America won the Revolution and the island became part of the new country?

In the end, it was the tree rings in those old timbers that gave up the date. Recently, Zachary Merrill of Great Lakes Dendrochronology determined the home’s construction as late summer or early fall of 1790. Merrill likes to say, “Trees don’t lie, but oral histories do. Things get passed down and get a lot more exaggerated.” In order to accurately date the McGulpin house, core timber samples of the house had to be compared to another building with a known date. “There has to be enough overlap between one chronology and another for it to statistically match,” Merrill explains. Samples from the McGulpin house matched up with another dendrochronologist’s research 50 miles across the water on Beaver Island from the old Mormon print shop, which is now the Historical Society.

Photo by Zach Merrill

Photo by Zach Merrill

Merrill’s study of the McGulpin House spanned the course of two summers. He started in 2021 by collecting 19 samples focused on the roof timbers. He chose to begin with samples from the roof because it was the most noninvasive part of the house. “I didn’t want to affect the appearance or architecture, or any of the places the public can see,” Merrill explains. After he was finished Merrill took each sample back to his office where he sanded them down with 1,000 grit sandpaper and measured the rings using digital measuring software. Some tree rings are so small that had Merrill tried counting the rings in the field—before sanding down the samples—his count could have been off by more than 100 years.

That first summer, Merrill ended up with an inconclusive date for the McGulpin House. “The dating was there,” Merrill says, “but it wasn’t there enough. I figured with more samples I could get a positive date, something I could stand behind.” So, the following year Merrill took samples from every area of the house he could reach without causing visual damage. He then compared the new samples to the old samples and came up with what he describes as a “robust chronology” for the house. He then matched that chronology with the building on Beaver Island and was able to conclude the McGulpin House was built in 1790. With that fact settled, we now know a lot about the context in which the home was constructed.

Photo by Mackinac Island State Historic Park

Flashback to 1790

The Revolutionary War has been over for seven years and President George Washington has recently given the first State of the Union Address in the young country’s then capital, New York City. Thanks to the Treaty of Paris seven years before, King George is to keep his hands off the 13 colonies as well as any land east of the Mississippi and north of Florida to the Great Lakes including Mackinac Island that had just squeaked under the northern boundary of the new country. But the Brits are taking their sweet time leaving the island, including Fort Mackinac that sprawls defensively along the limestone bluffs. “If there were any self-identified American citizens out here at the time, I’m not aware of them,” says Chief Curator Craig Wilson. “People were basically continuing as if nothing had really changed.” We can only speculate that one Brit went so far as to build himself a new house, his axe ringing out defiantly into the silence of the clear Straits of Mackinac air.

With nary an American citizen on the island to tattle to the authorities in the new country the Brit likely got away with his big trespass—at least for six years. The Americans took over Fort Mackinac in 1796 and pushed the British out—but not for good, as it turns out. The Brits retook the fort during the War of 1812. After America won that war in 1815, the Brits were pushed out, for the last time.

End of story? Not quite, there’s much historians still don’t know about the McGulpin home. Did the builder flee to Canada, sail back across the pond to his Mother Land or did he switch his allegiance to the new country? And for that matter, what was the Brit’s name? It wasn’t McGulpin. He was a baker for the American Fur Company, who purchased the home in 1817. Secrets all, that the old house has yet to give up.

Photo by Mackinac Island State Historic Park

Visit the McGulpin House

A new McGulpin House exhibit, which includes a short video program about architectural styles on the island as well as updated exhibit panels providing context in terms of what was happening on the island in 1790, opens on June 3. Find more info at mackinacparks.com.

Photo by Mackinac Island State Historic Park

Photo(s) by Mackinac Island State Historic Park