I had suspected for a long time, that HQ2 couldn't fit in a single city. I came about it the long way... I thought a lot about how the rough footprint of HQ1, and then imagined how you'd move that some place else. Plus future growth. It didn't make sense.
I think a lot of people got to it faster, simply by saying: why can't they figure it out themselves?
https://www.vox.com/policy-and-politics/2018/11/9/18067908/amazon-hq-2-new-york-virginia-dc-lic-crystal-city2