Tracking Changes in Walkability Over Time: How Our Neighborhoods Are Developing and What it Means for Health Surveillance.

An increasing body of evidence highlights the health-supportive role walkable environments can play by increasing active and reducing sedentary travel, thus lowering chronic disease risks. With increasing urbanization, it is important to assess how built environment characteristics are changing over time. In this context, understanding the extent of geographic and social disparities in the distribution of changes in walkability is also warranted. This study presents a nationwide assessment of how physical environment characteristics known to impact health and welfare are changing over time in the U.S. We integrate longitudinal data for over 164,000 participants in the American Cancer Society's prospective Cancer Prevention Study (CPS-3) cohort with objectively assessed built environment data at two time points (2013 and 2020). Descriptive and longitudinal change detection modeling of a geographically and ethnically diverse national sample of over 109,000 non-movers revealed some improvements in urban compactness, street connectivity, transit accessibility, urban diversity, and overall walkability levels. Changes in walkability across U.S. regions and the urban-rural continuum exhibited geographic disparities. Participants in rural areas and small towns experienced a modest reduction in walkability, whereas the reverse was observed for those in urban areas. Walkability increased over time for all age and racial groups but exhibited considerable variations. The increase in walkability over time was greatest for Hispanics and Blacks compared to non-Hispanic Whites. Results provide background trends and inform walkability interventions designed to reduce geographical inequities for the most underserved. Implications of our work for future research are discussed.