Curbing Urban Sprawl: A Study of Three Typical American Cities from the Perspectives of the Built Environment and Socioeconomics

Urban sprawl detrimentally impacts contemporary sustainable urban development and construction. While recent studies have explored the phenomenon of urban sprawl, most of these studies have been limited to the mere identification of urban sprawl without offering comprehensive urban nonlinear factors for effectively curbing urban sprawl. Hence, the study seeks to identify various urban factors influencing urban sprawl and to propose targeted strategies for mitigation. The study's timeframe encompasses the years 2010–2019 based on three cities with typical spatial structures and sprawl characteristics: Washington, DC, Chicago, and New York. In the initial phase, we conducted a comprehensive analysis of the built environment and the socioeconomic factors in these cities to fully understand their spatial characteristics. Subsequently, by calculating the urban sprawl index (USI), we unveiled both consistencies and differences in sprawl patterns across these three cities. Then, with employing a random forest model, we quantitatively explored the nonlinear relationships between these factors and the USI, effectively identifying key influencing factors and proposing targeted measures. Our research results identified that the important factors influencing sprawl patterns include the socioeconomic factors such as income distribution and employment arrangements, as well as built environment factors such as road networks. These findings provide scientific support and decision-making reinforcement for urban planning and development, promoting the optimization of urban configurations, curbing the trend of urban sprawl, and advancing sustainable urban development.