Just published "Planting for Posterity" - inspired by the alumni magazine article with the same title. https://giving.upenn.edu/planting-for-posterity/
Philadelphia has a total Tree Equity Score of 84. But 218 neighborhoods, out of 1,329 have a Tree Equity Score under 75. So, for every neighborhood in the City of Brotherly Love to have a score of 75 out of 100, almost a hundred thousand trees (97,712) will be needed to be planted. The city, generally, is doing so well that this is just a 1.8% increase in the tree canopy.
Sources: https://www.treeequityscore.org/reports/place/philadelphia-pa/ i-Tree Landscape, American Forests.