So, my old advisor made a statement wondering what things would have been like if Facebook had been around in 1963. I replied with a query that asked how much real estate the NSA would have needed to store all of the data it collects on punch cards. I just finished up with some homework and began searching for rough numbers on how much data you could store in a given amount of space using punch cards for that era. This was one of the first things I found.

Google's Datacenters on Punch Cards

You've got to change things around slightly to make it work for the NSA, but that's just arithmetic pretty much. There really is an XKCD for everything.