Where would new trees
help residents most?

What is measured, and what is estimated. Surface temperature (Landsat 8/9 thermal) is measured per area. Tree cover starts from the USFS / CAL FIRE 2022 California Urban Tree Canopy, a 0.6 m aerial classification of ground actually under tree crowns. Where that assessment is missing or too partial, a 2009–2020 height model fills in (in the Contra Costa builds rescaled onto the aerial line and checked against the county lidar map, which itself supplies some areas); a satellite greenness index stands in for the last 79 of 15,676 ranked areas. Every area shows its source in the app. The San Ramon, West Contra Costa and Pittsburg & Bay Point maps are finer views inside the county map, so the resident total counts the county, Bakersfield and Los Angeles once; the 15,676 ranked areas are records across the six maps. Surface heat is the median of summers 2024–2026 in every map. In Los Angeles, areas inside the January 2025 Palisades and Hurst fire perimeters are flagged, because their tree cover and residents predate the fires. Population and age are US Census ACS 2020–2024 five-year estimates allocated into areas; air-conditioning access is the Census LACE 2023 tract estimate, weighted zero in San Ramon and Bakersfield where it is near-universal. In Contra Costa County and in Pittsburg & Bay Point surface heat is weighted zero: the county spans marine to Delta, so a hotter area there is mostly a different climate, not a shade problem. Walking time in every build is routed on the OpenStreetMap pedestrian network to mapped libraries, community centers, pools and senior centers, whose hours and cooling status are not verified; the official county cooling directories are listed separately. Tree counts and costs are planning assumptions, not quotes. Every build carries a data & methods guide with sources and limits.