Problem, research strategy, and findings: In recent years, some economists and urban development advocates have argued that historic preservation is fundamentally at odds with a growing, diverse economy. We supply empirical support for Jane Jacobs's (1961) seminal argument about the value of “plain, ordinary, low-value old buildings,” finding that older, smaller buildings support dense, diverse streets and neighborhoods (p. 187). We use spatial regression models to analyze how social and economic activity relate to building characteristics in Seattle (WA), San Francisco (CA), Tucson (AZ), and Washington, DC. On a per commercial square foot basis, areas with older, smaller buildings and mixed-vintage blocks support more jobs in new businesses, small businesses, and businesses in creative industries. However, while areas with older, smaller buildings have greater diversity of resident age and higher proportions of small businesses, we also find lower proportions of Hispanic and non-White residents, indicating limited racial and ethnic diversity.

Takeaway for practice: Focusing on new construction alone to achieve denser, more sustainable cities elides the important role that older, smaller buildings play in dense, diverse neighborhoods. Planners should support the preservation and reuse of older buildings and the integration of old and new buildings. Relevant policies include adaptive reuse ordinances, performance-based energy codes, context-sensitive form-based coding, and deregulation of parking requirements.