Residential housing segregation and urban tree canopy in 37 US Cities; data in support of Locke et al 2021 in npj Urban Sustainability

Our goal in this paper is to examine whether there are similar
patterns in the distribution of tree canopy by Home Owners’ Loan
Corporation (HOLC) graded neighborhoods across 37 cities. A pre-print
of the paper can be found here: https://osf.io/preprints/socarxiv/97zcs This data packages contains: 1. City-specific file geodatabases with features classes of the HOLC
polygons obtained from the Mapping Inequality Project https://dsl.richmond.edu/panorama/redlining/ ,
and tables summarizing tree canopy, and in some cases other land cover
classes. 2. An *.R script that replicates all of the analyses, graphs, and
tables in the paper. Other double checks, exploratory, and
miscellaneous outputs are created by the script too as a bonus.
Everything in the paper can be done with the script; additional work
outputs are also created. 3. A *.csv file containing city, the HOLC grade, and the percent tree
canopy cover. This can be used to create the main findings of the
paper and this flat file is provided as an alternative to running the
R script to extract information from the geodatabases, combine, and
analyze them. The intention is that this file is more widely
accessible; the underlying information is the same. Redlining was a racially discriminatory housing policy established by
the federal government’s Home Owners’ Loan Corporation (HOLC) during
the 1930s. For decades, redlining limited access to homeownership and
wealth creation among racial minorities, contributing to a host of
adverse social outcomes, including high unemployment, poverty, and
residential vacancy, that persist today. While the multigenerational
socioeconomic impacts of redlining are increasingly understood, the
impacts on urban environments and ecosystems remains unclear. To begin
to address this gap, we investigated how the HOLC policy administered
80 years ago may relate to present-day tree canopy at the neighborhood
level. Urban trees provide many ecosystem services, mitigate the urban
heat island effect, and may improve quality of life in cities. In our
prior research in Baltimore, MD, we discovered that redlining policy
influenced the location and allocation of trees and parks. Our
analysis of 37 metropolitan areas here shows that areas formerly
graded D, which were mostly inhabited by racial and ethnic minorities,
have on average ~23% tree canopy cover today. Areas formerly graded A,
characterized by U.S.-born white populations living in newer housing
stock, had nearly twice as much tree canopy (~43%). Results are
consistent across small and large metropolitan regions. The ranking
system used by Home Owners’ Loan Corporation to assess loan risk in
the 1930s parallels the rank order of average percent tree canopy
cover today.