When Gavin Newsom was running for California governor in 2017, he famously vowed to “lead the effort to build the 3.5 million new housing units we need by 2025.” Newsom conceded that the goal was “audacious” but argued that “our solutions must be as bold as the problem is big.”1 Everyone agreed that California’s housing problem was big. What drew skepticism was the prospect of building 3.5 million homes by 2025.