Address clustering intuition

I've formed an intuition that, if all IP addresses were portable (ie.
independent of ISP) and assigned on a strictly geographic basis, then
there would *automatically* be clustering of addresses equivalent to
that obtained from CIDRization as a result of marketplace forces and
the practicalities of technology.

This turns out not to be the case at all. See the big-internet archives
for lots of messages on this. (Andrew Partan)