Anyone who has attempted to buy or rent a home in the past decade knows that there is a shortage of housing, and this lack of availability only worsens when searching for affordable housing. Though there are numerous drivers of this crisis, researchers, politicians, and community advocates alike are positting that land use regulations can play a significant role in exacerbating and mitigating the problem.
In their paper "Housing Affordability Crisis and Inequities of Land Use Change" in the Journal of the American Planning Association (Vol. 88, No. 1), Ajay Garde and Qi Song examine land use characteristics of 180 cities in the Southern California region to study how they contribute to region-wide housing inequities. The researchers studied land use characteristics of cities in 2016, changes in cities' land use characteristics over time, and the correlations between land use characteristics and socioeconomic characteristics of cities in the region spanning Los Angeles, Orange, Riverside, San Bernardino, and Ventura counties.
To do so, Garde and Song began with a cluster analysis and developed a typology of cities, based on the land use portfolio of each city in 2016, to highlight how these different types of cities address the region-wide housing crisis differently. For instance, land use portfolios of cities in the "high-density multifamily" cluster contribute most to address the region-wide housing crisis whereas those in "exclusive" clusters contribute the least.
Figure 1. Geographic distribution of eigth types of cities in the region.
Next, Garde and Song used several statistical techniques to examine whether land use portfolios of different types of cities are associated with socioeconomic characteristics of their populations. In addition, the authors analyzed the change from 2008 to 2016 in the share of residential land uses that accommodate multifamily housing and categorized cities using a "weakening–strengthening" continuum (weakening is a reduction in percentage of land for multifamily housing). They also examined cities using an "exclusive-inclusive" continuum (cities with over 70 percent of residential land use dedicated to single-family homes are exclusive), given that some cities in the region have no land dedicated to multifamily use.
Figure 2. Changes in land use portfolios from 2008 - 2016 broken into four types: exclusive and weakened, exclusive but strengthened, inclusive and strengthened, or inclusive but weakened.
Through their research, Garde and Song uncovered a few important findings:
Multifamily land uses were distributed inequitably in cities across Southern California, and the cities' land use portfolios were associated with socioeconomic characteristics of their populations. For example, the cities in the "exclusive" cluster had the largest percentage of single-family residential zones (89.4 percent) and the smallest percentage of multifamily and mixed land uses (0.9 percent). In general, exclusive cities had low population densities with a concentration of the affluent White population.
The land use changes in cities from 2008 to 2016 generally exacerbated inequities in the distribution of multifamily housing across the region. In cities in the "high-density multifamily" cluster, the changes in land use portfolios were inclusive and strengthened, meaning they had a significant share of land for multifamily housing in 2008 and continued to increase that share in 2016. In contrast, cities in the "exclusive" cluster had portfolios that were both exclusive and either weakened or unchanged from 2008 to 2016. Thus, out of 180 cities, 128 cities had either not addressed the existing land use inequities or intensified the issue.
Garde and Song ultimately conclude that most cities in the Southern California region cannot equitably address the region's housing needs, especially for low-income residents, unless they rezone to allow for multifamily housing. The state government should mandate that cities enact land use reforms aimed at correcting inequitable distributions of multifamily housing to address the housing crisis by requiring municipalities to allocate land uses based on population projections for all income groups as well as the existing land use portfolios of cities. This research also has implications for cities in metropolitan regions experiencing housing shortages, so similar research should be conducted nationwide.
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About the author
Anika Murasaki Richter is a master in urban planning candidate at Harvard University's Graduate School of Design.