[philipkglass]

That's interesting. I hadn't heard of this before. The evidence is pretty well set out in Kathleen Tobin's "The Reduction of Urban Vulnerability: Revisiting 1950s American Suburbanization as Civil Defence."

https://www.oftwominds.com/blogjuly10/Cold.War.Urban.Vulnera...

The vast majority of proposals are from before 1956 -- i.e. before the Soviets demonstrated their own high-yield thermonuclear weapons. The degree of decentralization required to mitigate against the multi-megaton bombs of the later 1950s would have been truly staggering.