What were the circumstances of the construction of the various buildings through which the boundary between Vermont and Quebec passes? In particular, what were the laws affecting construction on the boundary when they were built?
What I know includes this:
From Matthew Farfan's book The Vermont–Quebec Border I learned that these are called "line houses". Having learned that term from reading excerpts on Google books, I found it used in precisely that sense in three Wikipedia articles (one of which referred to a building on the boundary between Maine and either Quebec or New Brunswick), so I created links to a non-existent Wikipedia article titled "line house" and then I created that article.
At some point in the early 20th century, the International Boundary Commission was created, headed by two commissioners – one Canadian and one American. By treaty, no one can build within three meters (a bit less than ten feet) of the boundary without the Commission's permission. (That includes pipelines or electric power lines that cross the boundary, retaining walls, and of course, houses.)
The most famous border-straddling building is the Haskell Free Library and Opera house, intentionally built so that the boundary passes through the building. This was built in the first decade of the 20th century. Just east of it is what appears to be an ordinary-looking single-family residential house whose front door is in Vermont and whose back door is in Quebec. The border runs through a bunch of other buildings in that vicinity some of which look like industrial buildings.
The Joint Report upon the Survey and Demarcation of the Boundary between the United States and Canada from the Source of the St. Croix River to the St. Lawrence River, published by the International Boundary Commission in 1924, mentions "line houses", using that term, more than a dozen times.
In 1771–2, that part of the boundary was surveyed and marked with survey monuments by Collins and Valentine. In 1842 the Webster–Ashburton treaty said the measurement errors of Collins and Valentine would not be corrected, but rather the boundary would remain where they marked it. The aformentioned report published in 1924 said some of those markers were still intact.
Were the buildings through which the boundary passes
built before any law required authorization from the Commission or like permission, or
built in disregard of the requirement, or
built by permission, or