The city of Cambridge, MA maintains a wealth of geographic information on its GIS website. One of the more unconvential datasets is the list of trees lining the streets of the city. It contains the position and species of around 30 thousand trees and can be explored using the Cambridge Tree Walk) application. While this app is incredily detailed and useful at high resolution, it loses all information at low resolution. The identities and positions of the trees are lost. And if they weren’t they would be too dense to display in a meaningful and intelligible manner.
To provide a different view, I calculated which tree species is most common on each block in Cambridge and plotted the results using D3.js. The analysis shows that Maple trees dominate the landscape in Cambridge. Further down the list are Oaks, Lindens and Pears. While these are the most common trees on most street blocks in Cambridge, there are a few which are dominated by less common species. This isn’t to say that those species are only found on those blocks, just that those are the only blocks where those species are in the majority.
How useful is this map? I don’t know. But it was fun to make and will hopefully serve as a decent example for introducing how D3.js can be used for cartography at Maptime Boston. A tutorial describing how this map is made is available on the GitHub page for the project. It’s also avilable as a block.