Fascinating thread.
Having driven many times between Grand Isle, Vermont and Montreal I'd often been intrigued by "Missile base road" just north of the town of Arlberg and just south of the Canadian border.
Turns out, it was just that - the site of an ICBM silo, which in the sixties was the closest such installation to the "the enemy"
I believe the missiles in those silos were Thors.
The particular silo was only operational for a short period, but a local chap recounted how the missile was brought up to launch status during the Cuban missile crisis.
I also believe, the silo is flooded and the concrete doors(12 tons?) are permanently propped open as part of an arms limitation agreement so they can be monitored by satellites.