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This weekend we spent Diwali with our niece in suburban Philadelphia.  We were out in her backyard, when she saw a spider on a hedge with her new and focused eyes.  “Eek, a bug!”.  I hadn’t even noticed it (2 mm across), but I did note silently that it was an arachnid, not a hemipteran.

Only when we look closely at something and with understanding of what we are looking at do we really see it.  Before then, our prejudices about the way the world works obliterate all detail from what we see.  A broken clock is broken to me, but a fun electronic or mechanical project for others.  A broken city is a hopeless wasteland in a death spiral to many, but a place full of thousands of people interested in making their homes more livable to me.

I recently downloaded the “transportation means to work” for every block group in the country from the census.  I’d like to know where traffic is the minority mode, second to walking, biking or transit.  What do those places look like?  How many Americans live and work there?

I used to think “Means to Work” was a punk statistic. Commutes only represent 20% of the trips we make.  I have recently come to see the commute in a different light.  If somebody can walk to work, they are much more likely to live in a walkable place than someone who cannot.  Sure, they might be poor or religious, but it is much more likely they are responding to their built environment and opportunities  than economic or doctrinal forces.

I’m not yet done with the data, and I won’t bore you with it (yet), but I did notice something about it.  There are walkable places all over, and they are unanimously near city centers.  You don’t see things at large scales that you see easily at small scales.  Minorities, like walkers, are meaningless in the aggregate, but ubiquitous at specific locations.  They are still minorities, but they are not minorities evenly everywhere
This is important to pundits because they can look at things from different scales to get the answers they want.  I have seen gun control arguments be argued from state versus city data.  Both datasets are absolutely true, both support different conclusions.  Transit advocates like to look at the performance of particular neighborhoods or cities versus suburbs, while transit skeptics use equally true data from the region to argue against transit.

It’s why in my own book, I’m looking at the census block group level for the whole US.  Small enough to see things, big enough to work with, and consistent enough to cover the whole US.


At the end of the week I’ll talk about geometry and urbanization.