[khuey]

That's because nowhere near enough is approved. The US population growth rate is around 1%. If San Francisco were growing no faster than the country at large it would need to build housing for about 8500 people per year. San Francisco is currently building around 3500 homes per year.

And that's not even accounting for the massive economic boom going on here, or the surrounding municipalities which are largely doing worse on construction (cough cough Palo Alto).