OG Chris Elmendorf tweet here: x.com/CSElmendorf/...

And you can play with the web app here: contextual-upzoning.vercel.app

Full write-up here ⤵️ alexshadley.substack.com/p/ef779f2a-c...

Net net, we think contextual upzoning has promise. It may well be a path to solve the housing crisis long-term since zoning capacity automatically scales with pop growth, & it avoids the excesses of upzonings that are, in truth and not just in imagination, wildly “out-of-scale”

2) Are there undesirable, unintended side-effects to land economics? We describe one (perhaps desirable, perhaps not) example of an unintended incentive created. We suspect there are more, some of which may require policy tweaks

We have two buckets of concerns with this policy:
1) Political concerns. E.g., would there be political blowback if you legalized another salesforce tower without the value capture?

Breaking down the housing legalized by neighborhood, we learned:
- This policy has a huge effect in central business districts - think of Salesforce's lucky neighbors
- In SF it yields solid AFFH outcomes (Pac Heights being among the neighborhoods with the most housing legalized)

@alexshadley.bsky.social & I learned a few things from this web app:
- Bc of the right-skewed distribution of building heights & bulk, you want to anchor a contextual upzoning to the biggest building nearby, rather than the typical building nearby. Production-wise, it's not a close call

#2: The central complaint animating NIMBYs is a fear of “out-of-scale” development: a single building (eg 2700 Sloat) that will forever alter the neighborhood. Contextual upzoning addresses the kernel of truth in this critique—bc contextual upzoning is not one-size-fits-all

Here's why we think this policy is promising

#1: It yields an adaptive zoning buffer, to borrow @shanedenson.bsky.social's term. Zoning capacity is automatically created when & where new dense housing is built so it can scale w/ pop growth

We built a web app where you can play with a number of parameters to such a policy and see how many homes you can legalize in San Francisco by legalizing taller buildings nearby other tall buildings contextual-upzoning.vercel.app

A contextual upzoning is a policy that allows bigger buildings near other bigger buildings.

Take 300 16th Ave (pictured below). The city's 40-X district makes it illegal to build anything similarly tall nearby. Contextual upzoning would change that