Machias Seal Island

An Ongoing Border Dispute Between the United States and Canada

This is Machias Seal Island, a 20-acre island in the Bay of Fundy.

You can't see it? Let's zoom in.

Hmm. That doesn't help much. Let's zoom in some more.

There it is! It's a speck of land that barely appears on the map.

You can see the lighthouse in the photo above. The island is inhabited by 2 human lighthouse keepers, a few seals...

...and lots and lots of puffins.

The ownership of Machias Seal Island is disputed by the United States and Canada. Canada is in physical possession of it, but the United States has not formally dropped its claim to the island.
We've previously written several posts about the development of the US-Canadian border, which includes weird exclaves. Ambiguity about the border even led to the creation of 2 short-lived nations.

(Painting by Benjamin West of the American delegation at the Treaty of Paris)

Although the United States and Canada now maintain a long, peaceful border, the placement of that border has been in doubt since the Treaty of Paris (1783) in which Britain recognized the United States as an independent nation. That treaty attempted to draw borders over unexplored lands. The authors did the best that they could with their knowledge of geography. But, alas, one of the descriptions for the border between Maine and maritime Canada was problematic. The treaty says that US territory includes:

all Islands within twenty Leagues of any Part of the Shores of the United States, and lying between Lines to be drawn due East from the Points where the aforesaid Boundaries between Nova Scotia on the one Part and East Florida on the other shall, respectively, touch the Bay of Fundy and the Atlantic Ocean, excepting such Islands as now are or heretofore have been within the limits of the said Province of Nova Scotia.

IWeve bolded the parts of the text that are the source for the Machias Seal Island dispute.
As we've mentioned in a previous post, the eastern border of Maine was of great concern to the British. Some British officials coveted what Americans saw as their territory, and vice versa. Control of the Bay of Fundy was of great importance to British commissioners at the Treaty of Ghent (1814), which ended the War of 1812.

Now back to Machias Seal Island. The American argument is that it lies within 20 leagues (approximately 69 miles) of the coast of the United States.
The Canadian argument is that a land grant that pre-exists the Treaty of Paris defines the island as part of Nova Scotia. It built and has operated a lighthouse on the island since 1832.
Occasionally fishermen from the 2 nations have gotten into scraps about its ownership. Some Canadian citizens have staked mining claims to the island as a means of asserting Canadian sovereignty. The State of Maine has included the island on its maps of electoral districts.
But if possession is indeed 9/10ths of the law, then Machias Seal Island is Canadian. The United States has chosen not to press the issue.