This recent article by Bloomberg CityLab, about "how California set off a backyard apartment boom," has some interesting stats about the extent in which accessory dwelling units (ADUs) are quickly being adopted and delivered across the state.

For one, a majority (87%) of jurisdictions have enacted at least one ordinance related to ADUs, though many have several. These policies might include everything from by-right zoning to some form of financial assistance if you build. Here is a graph showing the cities and counties that have created ADU ordinances since 2013:

All of this has translated into housing supply. In 2019, California homeowners brought over 12,000 accessory dwelling units to the market (based on permits issued). Though a relatively small quantity based on the state's overall housing deficit, this number is surely growing thanks to policies and programs, like this one here, that are working to remove the barriers to building.

For the full CityLab article, click here.