Suppose Mary were to start building an artificial peninsula/jetty/etc. extending from Cape Cod and starts building east/ne, building up a real peninsula with rock/dirt/sand, etc, to the point where there’s arguably real land there, not a bridge. John, in Nova Scotia, starts doing the same thing and builds toward MA. Eventually they meet.
Clearly, there’s going to be much hemming and hawing over unauthorized marine projects and the new land bridge is going to eventually have to come down as it’s interfering with navigation, but given how governments work it’s not going to come overnight. The US’s EPA is going to demand a 5 year projective study on whether or not tearing down the land bridge will affect spotted owl habitats and the Canadians are going to spend months debating whether funding the teardown is a Federal or provincial matter and whether or not the engineering plan has to be in French too.
Where would the border be? Would the border be naturally construed as exactly “halfway” in some way, either in terms of distance from the old shoreline or in terms of travel distance (in case the new land snakes around)? Would there be an area in the middle that would still be legally consider “the high seas” and part of no country even though it is now land because it is outside of what were the territorial waters? For example, how far along the land bridge could someone starting on the US side walk along the bridge before they have a legal duty to check in with Canadian customs and immigration officials?
Would the border be different if Mary built the entire thing starting from the US and effectively pierced Canadian territorial waters and eventually the land with her construction?
Has anything like this ever actually happened anywhere in the world? Are there any jurisdictions that have explicit policies on how a new land bridge would affect borders?
Where a bridge crosses a waterway that defines a political boundary, the center of the bridge is generally defined as the border. In more complicated situations such as the one you describe, the border would normally be drawn in accordance with the UN Convention on Law of the Sea. Disputes would be handled (depending on the nature of the dispute) by the International Tribunal on Law of the Sea, Seabed Authority,International Maritime Organization, and Commission on Limits of Continental Shelf.
The US is not a signatory to the UNCLOS, but recognizes most of its provisions as customary international law. Whether any of those it has reserved on would affect your hypothetical dispute is… well, complicated.
Like every other border on earth, it’s decided by an agreement between the bordering parties, or undecided by the lack of such agreement in some cases. In this case, like all other US borders, it’s where we decide it is.
The border is only at the 49th Parallel west of Lake of the Woods. This hypothetical bridge is well east of that, and would go into currently international waters (although maybe not out of the EEZs, so they could just use that). Most Canadians live well south of it.
I realize this is a hypothetical, but when Mary starts blocking off access to Boston’s harbor (if not well before) someones going to stop it well south of the Canadian border. I assume Canadain shippers would be similarly watchful.
Victoria is already well south of the 49th parallel.
I’m trying to remember what international court issue was mentioning that a small island could not thwart a large mainland claim… IIRC it was the fishing dispute over the Grand Banks and Gulf of St. Lwarence, between the Canada/Newfoundland claim and St.Pierre and Miquelon claim of the French government - something along the lines of “hey, you’re not going to claim a third of the (formerly) world’s best fishing grounds based on a rinky-dink island beside a large mainland.”
But basically, yes, any terrirtorial and sea claims are going to ultimately be settled by negotiation… long before the breakwater reaches 3 miles, or 12 miles, or 200 miles.
In the middle of this two-lane “Friendship Bridge” you see a right-arrow in the West-going lane. No, the instruction is not to drive off the bridge into the Moei River, but just to get in the right lane for Burma’s traffic, opposite to Thailand’s. It would seem easier to do the traffic crossover at one of the bridge ends, but instead it’s done at the exact border.
(Zoom out to see the long cross-bridge trek tourists and day workers make. The urchins who buy cigarettes on the Burma side for resale on the Thai side take the much shorter route, across the Moei River, when cops aren’t looking.)
