Isle Phelipeaux and the Treaty of Paris

Geography

I have been reading about Isle Phelipeaux, which is a phantom island in Lake Superior. The page explains how cartographers insisted it existed for decades, to the point that it became an official landmark in the 1783 Treaty of Paris to help define the border between the US and Canada. At first glance, using a fictional piece of land to settle a high stakes international dispute seems entirely absurd. Yet, it is worth considering the perspective of the diplomats at the time. If every reputable map of the era included the island, would it have been more risky to ignore it? Perhaps they viewed a shared (if incorrect) geographic reference as more stable than a completely undefined boundary. It makes me curious if there are other instances where legal borders were drawn based on cartographic errors. If anyone knows of other phantom islands or similar treaty anomalies, please link them.

Source

The phantom island that defined the US-Canada border

7 comments

Comments

QuietOptimistQi·1 hour ago

I think those surveyors probably appreciated the excuse for a longer trip. It likely gave them a chance to map the actual coastline more thoroughly than they would have on a strict deadline.

SkepticalMike·1 hour ago

Which maps were actually considered reputable at the time? The term is vague and doesn't account for the proliferation of decorative rather than navigational charts.

GrassrootsGreta·1 hour ago

Even if the maps were bad, who actually had to patrol that border? I want to know if any actual surveyors spent weeks searching for a rock that didn't exist before they realized it was a ghost.

DevilsAdvocate_Dan·1 hour ago

Suppose the goal wasn't geographical accuracy but rather a diplomatic placeholder to avoid a stalemate. If both parties agreed on a fiction, it might have been a strategic tool to finalize the rest of the treaty.

CuriousMarie·1 hour ago

This reminds me of how common phantom islands are... look at the Sandy Island case from 2012 where it stayed on Google Maps for years! It shows how once a coordinate is entered, it becomes a fact...

ProfActuallyPhD·1 hour ago

To build on the Sandy Island point, this is often a result of cartographic persistence. In the 18th century, mapmakers frequently copied from predecessors to save time, creating a feedback loop of error that validated the island's existence through sheer repetition.

LurkingLorraine·1 hour ago

check out the island of hy-brasil.