The land area and population density differences are huge, but they're not really relevant unless they are the physical bottlenecks for housing construction in SF, which I presume they are not. Politics (namely, zoning) seems to be SF's bottleneck.
The amount of space impacts the politics as well, though. Seattle's new construction is largely converting ex-industrial zones to residential, not redeveloping existing residential zones, which is much easier to do politically. SF has had that kind of development too: much of SoMA is ex-industrial converted to residential. But there is not nearly as much ex-industrial land in SF compared to Seattle (or Oakland, for that matter).
I disagree, I think there's plenty of redevelopment. Just look at the controversies over allowing development on separate tax parcels, leading to new houses being built in side yards and back yards. There's also (on Capitol Hill at least) plenty of cases where single-family homes are being torn down for townhouses and apartments.
You can't do much "infill" development in SF while you still can in Seattle. That's very much a "physical bottleneck" that must be accounted for when comparing the two cities. In SF, if you want to build something, that means tearing something else down. In Seattle, there is still open space that can be built on. Of course politics plays a role, but lets not pretend that there aren't very real physical bottlenecks to building in SF.
> Of course politics plays a role, but lets not pretend that there aren't very real physical bottlenecks to building in SF.
There's a difference between "physical challenges" and "physical bottlenecks" to building in SF. Of course there are physical challenges. I'm claiming that the physical challenges are not the bottleneck, or in other words, if people were legally allowed to purchase property, tear down existing buildings if necessary, and build new taller buildings, I strongly suspect they would do so.
