An Assessment of Historical Planning Processes and Greenspace Distribution (1975–2024): A Case Study of Portland, Oregon, USA

The Portland study examined past planning regulations and greenspace distribution over the period of fifty years, with particular attention given to neighborhood differences between invested and non-invested neighborhoods. This exploratory study examined spatial greenspace using Normalized Difference Vegetation Index (NDVI) imagery. We tested the study hypothesis using the GIS Ordinary Least Squares (OLS) regression test to predict how key sociodemographic characteristics affect the provision of greenspace in non-white disinvested neighborhoods. The key findings suggested a consistent pattern of greenspace inequality, heavily shaped by historically disadvantaged ethnic status. Areas with higher non-white populations may have significant less greenspace (p < 0.001). Although median household income had a minimal negative impact, educational attainment showed a slight positive correlation. We employed multidisciplinary theoretical frameworks such as historical institutionalism, urban political ecology, and environmental justice. The study illustrated how historical decisions may have established path dependencies that are currently perpetuating greenspace inequalities. Policy solutions advocate for integrating restorative justice principles and rigid enforcement of 3-30-300 greenspace equity legislation to offset these long-term disparities.