[Cowen]

According to some napkin math with these figures[0], the three metro areas combined account for 11.7% of US GDP in 2012.

So yeah, I'm not sure what estimate they're using for the growth multiple from liberalizing land-use constraints, but if they're predicting a near doubling of the combined metro economies, it's safe to assume it's pretty high.

I do agree that land-use restrictions are currently holding all three cities back, my Friday night napkin math (read: probably wrong, way oversimplified math) just thinks their estimates are a little optimistic.

EDIT: Another question would be what's the time frame for this addition to GDP? 9% growth in one year is insanely great. 9% growth over ten years is insanely bad.

[0] http://en.wikipedia.org/wiki/List_of_cities_by_GDP

[raldi]

Which part of this chain do you think is the weak link?

1. If SF had typical land-use policies, it could build enough homes to accommodate twice its current population

2. If they did that, they'd be able to fill those homes with people

3. Those people, upon arriving, would have approximately the same productivity as current San Franciscans

4. SF would thus double its contribution to the US GDP

[robrenaud]

It's not as though those contributions come for free though. If talent leaves other places to go to NYC/SF/SJ, those other places become less productive.

[raldi]

Not necessarily, on a per-capita basis. If Alice has incredible pineapple-farming skills and is terrible at everything else, and she moves from Alaska to Hawaii, she improves both states' per-capita GDP.

[WillPostForFood]

1 is true, 2 and 3 might be true, but there are many variables that could lead to other outcomes. Double the density, you might lower the desirability, driving the current high GDP producers out. Then you have a downward spiral as revenue drops, incomes drop, rents drop, vacancies rise, crimes rises. Or it could be the next Tokyo. But there is no certainty.

[sukilot]

San Francisco has plenty of room for all the high GDP employees. They are paying high rent and pushing out low GDP employees.

[eastbayjake]

> Another question would be what's the time frame for this addition to GDP?

The actual paper[1] simply says that "lowering regulatory constraints in New York, San Francisco, and San Jose cities to the level of the median city would expand their work force and increase U.S. GDP by 9.5%", so whatever timeframe it would take to reduce those regulatory constraints. (In SF that sounds like a project measured in decades, although maybe the imbalance in supply and demand will cause a breaking point that forces the city to engage with real solutions to the problem.)

[1] http://eml.berkeley.edu//~moretti/growth.pdf

[bane]

You're only counting those areas specific GDPs. But I bet if you look at the components of GDP they contribute to by making markets available to the rest of the country (for example) it's far higher.

For example, NYC is home to much of the publishing industry. But all those books go out to local bookstores where they are sold at a small profit, increasing the GDP of those local areas above and beyond NYC's publishing industry's contribution.