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

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

Senate Bills 9 and 10, which will take effect on Jan. 1, 2022, will make it easier for Californians to build more than one housing unit on single-family lots and for cities to allow small apartment complexes in neighborhoods near public transit.