https://www.mercurynews.com/2021/09/17/what-californias-new-sb9-law-means-for-single-family-zoning-in-your-neighborhood/

Gov. Gavin Newsom this week signed a pair of bills into law that effectively put an end to traditional single-family zoning restrictions in most neighborhoods statewide.

Senate Bills 9 and 10, which take effect Jan. 1, 2022, will make it easier for Californians to build more than one housing unit on many properties that for decades have been reserved exclusively for single-family homes and will give cities greater flexibility to place small apartment complexes in neighborhoods near public transit.