Do Smart-Growth-Related Built Environments Promote Housing Affordability? A Case Study of Three Counties in the Portland Metropolitan Area

This paper focuses on whether smart-related built environments are associated with improved housing affordability for economically disadvantaged groups. Smart growth is a planning theme that aims to address the unintended negative consequences of urban sprawl through combining diverse dimensions across land-use diversity, housing diversity, accessibility, and compact development. Focusing on Clackamas County, Multnomah County, and Washington County within the Portland metropolitan area, the analysis uses census-tract-level data to assess both contemporaneous associations in 2013 and changes in affordability between 2013 and 2019. Overall, the findings suggest that smart-growth tools exhibit both potential and limitations with respect to housing affordability. Greater housing-type diversity and lower reliance on single-family residential land use are consistently associated with higher shares and subsequent increases in affordable housing units for low-income groups. In contrast, other smart-growth features—such as land-use mix and accessibility—show weaker or uneven relationships. These findings suggest that smart growth can contribute to expanding affordable housing supply primarily through housing-related components, while other dimensions of smart growth appear to play a limited role. The results underscore that housing-focused strategies play an important role in shaping affordability outcomes under smart growth.