Portland is “going to look like San Francisco in 10 years,” predicts real estate broker Douglas MacLeod. That’s because people like him are buying homes, demolishing them, and replacing them with two, three, or four skinny houses–houses as narrow as 15 feet in width but (unlike row houses) with around ten feet of space between them.

This continuing process has enough Portlanders upset that the city council recently voted to require developers to notify nearby homeowners at least 35 days before they begin demolition of a home, not that the homeowners will be able to do much about it. It has also led the Oregonian to commission these interactive graphics showing where homes have been replaced and how fast they are being demolished.

Of course, few are willing to discuss the real answer, which is to abolish or at least greatly enlarge Portland’s urban-growth boundary. The 2010 census found that Oregon is 98.8 percent rural, and more than 80 percent of its residents are confined to the remaining 1.2 percent that is urbanized.

Whenever anyone suggests expanding the boundary, people get hysterical about the loss of prime farmland. This is absurd, as proven by a 2001 study commissioned by none other than 1000 Friends of Oregon. As documented (but carefully couched in dire terms) in this publication, the study found that 5.9 percent of the Willamette Valley, home of Oregon’s best farmland, had been developed by 1990. If all land-use rules were eliminated, the study calculated, this would increase to 7.6 percent by 2050–hardly a great cause for alarm. (You can read more about this study in my old web updates.)

After a recent visit to San Francisco where I saw thousands of row houses crammed together on the hillsides, the Antiplanner doesn’t believe that Portland is going to turn into San Francisco by 2025. But Portland prices are rising rapidly–more than 30 percent in the last three years according to the Federal Housing Finance Agency, which will only increase the rate of demolitions. While prices haven’t reached San Francisco levels yet, the idea that people aspire to turn Portland into San Francisco, and that many residents agree with the goal, shows how poorly people understand basic economics.

Update: Someone pointed out that what the developer said was that if Portland didn’t allow skinny houses, Portland would look like San Francisco in 10 years, meaning Portland would be as expensive as San Francisco. That’s an interesting twist, but the truth is that San Francisco has tens of thousands of skinny houses and row houses and it is still expensive. It is expensive for the same reason Portland is expensive: urban-growth boundaries that contain 99 percent of the residents of the nine-county area in about 16 percent of the land area of those counties (in the case of Portland, it’s 94 percent of people inside 14 percent of the three-county area, not counting Washington’s Clark County). Making housing denser has not prevented either Portland or San Francisco housing from being expensive and volatile.