Diana Ionescu wrote:

Reducing or eliminating single-family zoning has been a hot topic in recent years as cities and states struggle to create more affordable housing and keep up with rising demand. "So far only Oregon has passed a state-level ban on single-family house zoning. If California’s S.B. 9 gets final passage and is signed, it would add a state of 40 million to the list." 

A second bill passed by the California Assembly this week, SB 10, "would allow local governments to rezone parcels up to 10 units with no environmental review, which would speed development by shrinking the rezoning process by several years." Proponents of statewide zoning reform argue that because "U.S. metropolitan areas operate as a contiguous economy, while their housing markets are fractured by dozens of cities and suburbs that each have their own regulations," more comprehensive state-level policies are crucial to solving the housing affordability crisis.