[fraserharris]

The best way i've seen this framed is: in all of the US, there are only about 2,000 blocks of housing with sufficient density & walkable services to support car free living. This is some of the most sought after and expensive real estate in the country, but zoning codes won't allow more of it to be built.

Example zoning restrictions: mandatory building setbacks, mandatory parking requirements, mandatory building separations, maximum units per building, 1 or 2 story maximum heights, high minimum lot sizes.

Note: a significant % of those 2,000 blocks are in San Francisco.

[pgwhalen]

Manhattan alone is on the order of 2000 blocks, I don't know where you came up with that figure.

[fraserharris]

Poorly recalling from my memory. Given that a "block" is a variable metric, the actual number is less important than the concept that it is a static. There are only ~5 cities in the US with > 1,000 of these blocks: NYC, Boston, DC, SF, Chicago (Philadelphia?, Baltimore?)* AND with a transportation network that makes car-free living possible. Developers would build more such areas if zoning allowed.

* Forgive my ignorance for being from the West Coast. Even in SF its difficult to live car free if you don't live on BART or Muni Metro.

[raldi]

This is very interesting, but I can't use it unless you have a reference I can cite.

I'm also curious how many units there are in those 2000 blocks.

[DrScump]

  high minimum lot sizes.

I'm confused. I can hardly think of an area with smaller average single family house lot areas than SF.

[fraserharris]

Exactly. Developers are economically incentivized to subdivide to the maximum extent. Low minimum lot sizes encourages small lot sizes = high density.

[runamok]

Right. Something like a third of Manhattan buildings could not be built today due to similar zoning restrictions.