200 Years

Interesting data visualization of the spread of US Post Offices from 1700 to 1900:

You can actually watch the train tracks being built across the midwest from 1870 on.

As Chris Blattman observes, this is a good reminder that the infrastructure required for meaningful development gets built in slow-motion.  I would love to see this map updated in 89 years to include the ongoing contraction of post offices.  I suspect that rate of contraction will mirror the expansion from 1800-1850 or so, and I wonder what year the number in 2100 will match.  I'd guess around 1800.

Following on Blattman's observation, I would be interested in seeing a map like this for cell phone towers (perhaps there is one already).  It doesn't take as long to put up a tower as it does a bland brick Post Office (in terms of actual labor; I'm not including the permit/public hearing process here), but there are unique infrastructure and location requirements for a cell tower that don't exist for a stand-alone building in a (presumably) already-populated area situated on an existing transportation route of some sort.  Therefore, I imagine that there's an acceleration of infrastructure build-out as the prerequisite pieces get assembled.

via Blattman.