One of many fascinating details in the Underground Space Center Library archives at the Canadian Centre for Architecture is something found in a paper, written by a University of Minnesota law student, called "Zoning Ordinances as Obstacles to Earth Sheltered Housing: A Minnesota Perspective." 
[Image: Random basement floorplan].
There, amongst other key legal points, the student weighs in on what he calls the "definitional problems" that arise when traditional zoning law is applied to underground space—indeed, "whether zoning regulations apply at all to underground structures."
Though the paper clearly focuses on the state of Minnesota, it goes as far afield as Texas; in the case of Hancox v. Peek, for instance, "a Texas Court of Appeals held that a fallout shelter which was wholly underground, except for a concrete slab which extended a mere two or three inches above the ground, was not a building—merely an appurtenance, and therefore not within the contemplation of a zoning ordinance requiring a minimum distance between buildings and adjacent property." One can easily imagine byzantine courtroom arguments and legal appeals of the future, citing legal precedents from wartime bunker construction, domestic fallout shelters in Texas, and perhaps even subsurface mine-safety regulations in some strange Kafkaesque scenario involving, say, the late Mole Man of Hackney and his contested underground estate.
But, as it happens, my reference to mining safety is deliberate. 
[Image: Random basement floorplan].
At the time of the paper's writing—the late 1970s—underground facilities, from parking garages to hospitals and private homes, were considered so novel from the perspective of traditional Minnesota zoning law that there was no accepted legal means for how to define or describe them. These are the "definitional problems" mentioned above. "Examples," we read, "are the broad definitions of basement and cellar... defining excavations of greater than 400 cubic yards as 'mining'—thus requiring a special permit, and defining 'detached dwelling' as one 'entirely surrounded by open space'."
That's worth repeating: excavations of greater than 400 cubic yards were legally zoned as mines—whether it was a parking garage or your newly renovated basement rec room.
In other words, if you lived in Minnesota in the 1960s and 70s, and you had a particularly enormous basement, inside of which you and your siblings might have watched television, you could, legally speaking, have been playing inside a mine. Whether or not this gave you permission to harvest minerals is unclear. 
[Image: A continuous mining machine at work; image courtesy of Salt Union Ltd].
No lawsuit, to my knowledge, has ever been retroactively filed against Minnesotan parents, accusing them of mine-safety violations—but there is always a first time.
Nor has the reverse of this scenario—in which a Minnesotan industrial minerals magnate from St. Cloud successfully rezones his mine or quarry as a domestic basement—been, to my knowledge, attempted.
#CCA
