Examining spatial patterns in affordable housing: the case of California density bonus implementation

California State Density Bonus Law A 65915-18 financially incentivizes housing developers to produce affordable housing by granting density bonuses to those who designate a percentage of the total units for residence by low or moderate income households. By incorporating affordable housing units alongside market-rate units, state density bonus law fosters opportunities to enhance neighborhood level socio-economic diversity. This paper investigates the effectiveness of density bonus policy at promoting socio-economic diversity within the City of San Diego by examining locational patterns of density bonus implementation and neighborhood demographic characteristics. This study utilizes spatial and non-spatial statistical analyses to identify trends and correlations in density bonus usage, housing stock, and racial and economic characteristics. The results indicate that density bonus usage in San Diego has not fostered socio-economic integration; rather its usage is clustered in neighborhoods characterized by high concentrations of Hispanics, Blacks, and multi-family housing units. The findings underscore the need to refine supply-side affordable housing tools so that they are effective in a range of land markets, and not only in the traditionally lower value land markets where minority households tend to reside.