A Bad Map and Border War Led to Isle Royale Being Part of Michigan


The Canadian shoreline can be seen in the distance from Isle Royale’s Mt. Franklin. Photo by Doug Marrin.

Tucked away in the northwest corner of Lake Superior is Michigan’s Isle Royale National Park, a true gem of wilderness that is easily forgotten partly due to its proximity to Canada and Minnesota and distance from Michigan. Isle Royale is 55 miles from the tip of Michigan’s Keweenaw Peninsula but only 15 miles from Canada.

The international boundary shows a distinct hump to include Isle Royale with the U.S. when it is much closer to Canada. Source: Google

Why is Isle Royale a part of the United States and not Canada?

A bad map.

The peculiar question of why Isle Royale is a part of the U.S. and not Canada can be traced back to an antiquated map used during key negotiations between the two countries. The original discussions around the U.S. and British Canada boundaries began after the American Revolution. The prominent 1783 Treaty of Paris was the defining document, with American negotiators such as John Jay, John Adams, Benjamin Franklin, and others leading the discussions.

The primary source for drafting these boundaries was a 1755 map crafted by John Mitchell. According to the map, Article 2d of the treaty determined the following border between the U.S. states and territories and Canada (parenthesis added by the author for clarification).

…thence through the middle of said Lake (Huron) to the Water Communication (St. Mary’s River) between that Lake and Lake Superior; thence through Lake Superior Northward of the Isles Royal & Phelipeaux to the Long Lake; Thence through the middle of said Long Lake and the Water Communication between it & the Lake of the Woods…

This map, although expansive, measuring almost six and a half feet wide and four and a half feet high, was riddled with inaccuracies. For instance, features like Isle Phelipeaux southeast of Isle Royale did not exist, and the Mississippi River was depicted inaccurately. And, just what was the “Long Lake” at the mouth of a non-existent river flowing directly from Lake of the Woods into Lake Superior?

The 1755 Mitchell Map showed the non-existent Isle Phelipeaux and questionable Long Lake at a non-existent river. Source Wikipedia

When looking at Isle Royale's positioning in relation to modern-day maps, the boundary set by the Treaty of Paris does seem confusing. While the more settled areas of Mitchell’s map were more accurate, the northern wilderness had only a few explorers taking measurements from a rocking voyageur canoe and the dense coastal growth to chart the expansive water and land. Yet, this boundary was accepted due to the Mitchell map's prevailing authority.

This error remained unaddressed until after the War of 1812, culminating in the 1814 Treaty of Ghent, which aimed to arbitrate all boundary issues, prompting further surveys. However, it wasn't until the summer of 1822 that there was a clearer understanding of the actual geography of Lake Superior and surrounding areas. And true to human nature, border disputes arose over the clarifications.

A significant turning point in the boundary discussion came in June 1842 when Daniel Webster negotiated firm boundaries with Great Britain, setting the definitive border from Lake Superior to Lake of the Woods, including Isle Royale's inclusion in the U.S.

But why, then, is Isle Royale a part of Michigan and not Minnesota?

All of the above plus the Toledo War.

When proposals to officially recognize Michigan as a state were first made, the Upper Peninsula was not part of the initial design. This region was originally a portion of the Northwest Territory, later merging into the Indiana Territory in 1800. However, in 1805, the area transitioned to the newly formed Michigan Territory.

Source: Wikipedia

During the early 19th century, Michigan's Keweenaw Peninsula, located in the Upper Peninsula, became a hotspot for copper mining. Due to its rich copper deposits and geological resemblance to the Peninsula, Isle Royale was naturally seen as an extension of these mining pursuits. This early economic interest strongly tied Isle Royale to Michigan's burgeoning copper industry, creating a deeper political association than with neighboring Minnesota.

Abandoned copper mines mark the connection to Michigan’s Keweenaw Peninsula copper trade. Photo by Doug Marrin.

The Toledo War, a border conflict in 1835 between Michigan and Ohio over a lucrative strip of land with the Maumee River, surprisingly escalated to the point where both states readied their militias. Despite the tensions, the dispute was relatively bloodless, with just a single reported casualty. The resolution was a compromise. Ohio received its desired border, while the nascent state of Michigan was rewarded with the inclusion of Isle Royale and the Upper Peninsula. Isle Royale officially became part of Michigan when the latter joined the Union in 1837.

By the time Minnesota achieved territory status in 1849 and later statehood in 1858, Isle Royale's affiliation with Michigan had been solidified.

Today, Isle Royale National Park is a breathtaking wilderness sanctuary filled with moose, beavers, and wolves, drawing hikers, campers, and nature enthusiasts from all corners of the world.


Lake Superior Magazine, Oct. 5, 2017.

National Archives – Treaty of Paris (1783)

Star Tribune Media, Apr. 19, 2019


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