The Paradox of Housing Supply Growth: Conservative Sprawl and Liberal Infill in the 21st-Century United States

Housing affordability is declining in the United States. To explain this phenomenon, many scholars and policymakers point to slowing construction, which they argue is particularly troublesome in coastal, liberal metropolitan areas. How does that claim align with recent trends? I examine housing supply changes among cities, counties, and metropolitan areas from 2000 and 2020, testing relationships between housing, politics, and demographics. My findings both confirm and belie conventional wisdom, producing a nuanced picture that highlights how prior development informs outcomes. Additional housing supply was disproportionately located in sparsely developed, greenfield areas in higher-income, ideologically conservative locales, typically in the Sunbelt and in states with Republican party-led legislatures. Infill area growth was slower but—in contrast to the overall trend—more likely to be located in liberal cities, counties, and metropolitan areas outside the Sunbelt. People in many liberal areas were more likely than those in conservative areas to live near new housing.