Mayor Bloomberg says New York City’s lack of affordable housing is a sign of a vibrant economy, because it proves people want to live there. Despite his reputation in the business world, he obviously doesn’t understand the laws of supply and demand.

“Somebody said that there’s not enough housing,” Bloomberg said on a radio show. “That’s a good sign.” Housing is only scarce, he said, because “as fast as we build, more people want to live here.”

In fact, as I showed in chaper 10 of my book, American Nightmare, as well as in this blog post, high housing prices do not prove that lots of people really find an area desirable. Instead, they are more a sign of government barriers to housing. In a nutshell, downward sloping demand curves means a few people may be willing to pay a high price for any good, but that doesn’t mean the public in general finds that good to be particularly valuable.

As reported by Virginia Postrel on Bloomberg’s own news service a few months ago, America’s elites have built an economic wall around places like New York City and California in order to make these areas more exclusive. Rent control in the city combined with New Jersey’s and Connecticut’s smart‐​growth policies have turned New York from a fairly affordable place to live as recently as 40 years ago to one that is completely unaffordable today.

Yes, Bloomberg’s city may be building some housing. But it obviously isn’t building enough to meet demand. In 1969, median housing prices in the New York urban area (including northern New Jersey) were just 2.6 times median family incomes, and 3.3 times in 1979. By 2005, they were 8.4 times. Thanks to the recession more than new housing, they were down to 5.3 by 2012–still way too high. But in New York City alone median prices were still 8.7 times median family incomes.

Here’s the surprise: Median family incomes in New York City were just 15 percent greater than in the city of Houston in 2012. But home prices were 284 percent greater. That’s not a sign that people are demanding to live there; it’s a sign of acute shortages.

Houston frets when its median home prices approach $150,000 and price‐​to‐​income ratios come close to 2.2. With New York City median prices approaching $480,000 and median values nearly nine times median incomes, Mayor Bloomberg should do more than pat himself on the back; he should recognize that the city is suffering from a major housing crisis.