How to prioritize park equity investments more efficiently: Introducing the per square mile tool

Existing tools to prioritize park investments do not identify locations that would maximize access for the greatest number of people, especially underserved populations. The first goal of this paper is to address this limitation by introducing a new tool for prioritizing equitable park investments using a utilitarian framework to maximize impact. The PerSquareMile (PSM) tool ranks one-square-mile cells to identify where new parks are needed within a given geography (e.g., a metro area) to provide access to the largest number of residents living more than half a mile from a park. The second goal is to demonstrate applications of the PSM tool, including identifying areas where biodiversity conservation and restoration can provide access to nearby nature for people who currently lack it. Using the PSM tool, we found that more than one-fifth of California residents lack a nearby neighborhood park and that a fraction of the total new parks needed could serve the majority of people in need. The third goal is a detailed comparison of the PSM tool with a similar Trust for Public Land (TPL) tool widely used in the field. We found significant differences between the two tools. The PSM tool enables users to identify priority areas for new parks to achieve distributional equity and utilitarian outcomes, thereby providing park access to the greatest number of people in the greatest need, as efficiently as possible. We therefore conclude that the PSM tool could inform park equity initiatives that seek to efficiently and equitably prioritize investments.