What Is the 'Gray Zone' Border Between the U.S. and Canada? | National Geographic

The United States and Canada share the longest undefended border in the world. Most of the time, it's as peaceful as it sounds, but not always. Since the 1700s, a tiny turf war has been smoldering between the two countries. The grand prize: an uninhabited island in the Atlantic Ocean and a nearby rock.

Welcome to Machias Seal Island. The island lies just off the coast of Maine and Canada's Grand Manan Island. It's so small that it could fit into New York City's Central Park more than 40 times over. But this area of the sea is known as the gray zone because the U.S. and Canada both claim it, and neither one seems ready to back down.

Why? Old paperwork, national pride, and lobsters—lots of lobsters. In 1783, the treaty that ended the Revolutionary War put Machias Seal Island under U.S. control, but Canada said, “Not so fast.” According to the land grant that founded Nova Scotia, the island belonged to Canada. The countries have been quietly jockeying for island supremacy ever since.

Canada's made the biggest land grab so far, building a lighthouse there in the 1830s. The U.S., meanwhile, pretends that the lighthouse isn't there because, gray zone. This all sounds pretty polite, but sometimes the tension escalates. The U.S. Border Patrol stopped a lot of Canadian fishing boats in the area in 2018. It said it was enforcing immigration laws and other violations of federal law.

The Border Patrol didn't arrest anyone and claims the stops were routine, but some Canadians ID them as a potential flexing of American muscle. Canada's fisheries minister expressed concerns, saying that lobstermen from the two countries have happily worked side-by-side. That's mostly the case.

The gray zone is chock-full of valuable lobsters. Lobstermen's tempers have sometimes risen and ebbed with the price of the catch over the years. Lobstering squabbles have occasionally rocked the boat in the gray zone, especially when market prices are going up. But things are generally copacetic.

It's all the same to the puffins and other birds that live on the island, which is an important seabird colony. They're studied by a handful of researchers and visited by up to 30 tourists a day—15 from Canada and 15 from the U.S. But until the neighboring nations decide that this dispute is for the birds, things in the gray zone are likely to stay gray. Locals are holding their breath for the next brew's national ego.