If you go to San Francisco, you're going to find it full of wealthy people—and Mayor Bill de Blasio claimed Friday that the constrained housing supply, not big tech, is to blame.

The mayor made the claim while pushing back on a suggestion from WNYC host Brian Lehrer that the impending relocation of Amazon to Long Island City would make New York City as expensive and exclusive as the Bay Area, which has become the capital of Silicon Valley. De Blasio, who has placed the loosening of height and density restrictions at the heart of his affordable housing plan, argued the problem was the city's historic resistance to development.

By contrast, he noted New York City's comparatively more relaxed regulations had allowed the construction of vast public housing system and—more recently—tens of thousands of middle- and low-income apartments.

"We need to really examine the difference between us and San Francisco. San Francisco made a decision a long time ago not to expand public housing, not to build up and create affordable housing on a substantial scale, by freezing in place what they had," the mayor said. "And it's beautiful—don't get me wrong—it's a beautiful city. But by freezing in place what they had, they created a pathway to a city of an elite."

De Blasio argued that bringing Amazon's second headquarters to Queens would expand the local tax base and allow the city to finance new subsidized units and repairs at New York City Housing Authority projects.

"The absolute difference between us and San Francisco is we believe in economic diversity, we believe in ensuring there's a vast supply of affordable housing," the mayor said.

His housing plan also called for robust creation of market-rate units, not just to subsidize low-income apartments but to meet the demand for housing created by job gains in New York, which have ranged from 60,000 to more than 100,000 for most years since the Great Recession. Silicon Valley's tech boom fueled a demand for housing that was not met by an increase in supply, leading to bidding wars that drove the price of simple homes into the millions of dollars. It also pushed people farther from their jobs for housing they could afford, resulting in long commutes.