American Forests, which is a US non-profit conservation organization, publishes something that they call a Tree Equity Score. What it effectively does is map tree cover across US cities. You can explore what that looks like, here. The score considers things like tree canopy, population density, income, race, as well as many other factors, and then produces a single score from 0 to 100. A score of 100 means that a neighborhood has achieved "Tree Equity."

There is seemingly a lot that you can glean from this score. For one, American Forests have found that income and race tend to correlate with tree canopy. Lower income neighborhoods tend to have less of it and rich neighborhoods tend to have more of it. You can start to see what that looks like in the Instagram post embedded at the top of this post. If it isn't showing up, click here.

But the other thing that is clear from these images is that rich people tend to consume more space. The richer tree-canopied neighborhoods appear to be less dense. The lots are bigger. And there are instances where the homes look to be adjacent to some large contiguous green spaces. This, of course, is a natural market outcome.

The Tree Equity Score tries to correct for this in its methodology. If a neighborhood's population density is very low (less than 2,000 people per km2), then it gets a higher tree canopy adjustment factor. It should have more trees. Conversely, if a neighborhood's population density is high (over 8,000 people per km2), then it's acceptable for there to be less trees (lower adjustment factor).

That said, it would be interesting to see a direct comparison of two neighborhoods -- one rich and one poor -- that have the exact same population densities and overall built form. I think that would speak volumes about tree inequity. I am also very curious about the global relationship between density and household incomes.

If any of you have a good source, please share it in the comment section below.

The out of office responder is on. I am currently on a multi-day stopover in Lisbon on my way to Malaga, Spain. One of my oldest friends (we went to elementary school together in Toronto) is getting married there this weekend. They chose Spain because that's where they met (she is Parisian). They have an incredible love story and I'm looking forward to celebrating with them in a few days. The above photo was taken with my iPhone from Sky Bar. The green you see in the foreground is Av da Liberdade. Here is another photo from a different angle, where you can begin to see the water (Tagus). Its tree canopy is one of the most impressive that I have ever seen. Its grandeur (largely its width) is quite a contrast against the small and winding streets in the rest of Lisbon. And it may be one of the only level places in this exceptionally hilly town. I'm a big fan of Lisbon, already.

The MIT Senseable City Lab recently developed something called the Green View Index. It is a measure of a city’s tree canopy. Below are the GVIs for Boston (18.2%), Geneva (21.4%), London (12.7%), and New York (13.5%). You may have to zoom in.

And here is a screenshot of Toronto. We have a GVI of 19.5%.

The index was developed by methodically scanning for trees in Google Street View panoramas. The reason street view was used – as opposed to aerial photography – was so that they could capture the human experience at street level.

All of MIT’s interactive city maps can be found here. It’s also interesting to pan around and see which neighborhoods are the greenest – particularly if you are familiar with the city.

One thing I noticed is that large green spaces such as Central Park, High Park, and Stanley Park don’t show up as very green. And that’s because the index uses car-based street view data. I feel like these green spaces should count for something though.