[jacobolus]

Currently about 3/4 of the land area of San Francisco is zoned to only allow single-family houses or duplexes. All of the pale yellow areas in https://sfplanning.org/sites/default/files/resources/2019-02... (RH-1 and RH-2 zones).

Most of that area is not classified as historical, and a lot of it is filled with relatively cheaply constructed and not particularly beautiful buildings (property values have increased a lot in the past few decades). The residential streets in most of that area are way wider than currently necessary and there is a lot of free or cheap street parking everywhere, but some arterial roads are a bottleneck during commute hours and public transit is inadequate. The zoning is basically “sleepy low-density beach town” rather than “cosmopolitan city”.

Changing the zoning of most of those areas to the purple (NCT) or medium orange (RM, RC, RTO) types is not the only change needed, and it won’t make a difference overnight, but it would eventually allow something like doubling the population of the city without requiring anything taller or larger than 4–10-unit low-rise buildings. It would probably also force the city to make a bunch of public transit upgrades, as the whole western half of the city is currently pretty isolated from the more connected eastern half.