Introduction


Seattle, Washington is known as the “Emerald City” due to its abundance of trees, parks, forests and other green spaces. But beyond environmental merit, accessibility to green spaces also provides a significant social benefit to city residents. A 2016 report from the World Health Organization found that urban green spaces provide psychological relaxation, physical activity and a reprieve from air and noise pollution, thereby promoting mental and physical health and reducing mortality rates. However, because lower per capita income is often associated with higher morbidity and mortality rates, I am interested in the distribution of Seattle’s green spaces, specifically in lower-income areas. Using data from Seattle’s open data portal, I will assess my hypothesis that, of Seattle’s seven districts, those with the highest median household income will be the most green, while those with the lowest median income will be the least green.

One of Seattle’s almost 500 parks in the shadow of the Space Needle.


DISCLAIMERS: Because many of these visualizations were created using large data files, they may take longer to load. They will load eventually. Links to all data sources will be provided at the end of the report.

library(tidyverse)

Tree Canopy


First, let’s look at the change in Seattle’s tree canopy over the past two decades. In blue, you can see Seattle’s tree canopy in 2003, while in red, you can see the tree canopy from 2016.


Figure One:


There is substantial overlap that is difficult to discern, but it is evident that more trees have been cut down in the southern half of the city, while more trees have been planted in the northern half of the city. Because it is difficult to distinguish, however, I will provide a graph of Seattle’s total tree area in 2003 and 2016.


Figure Two


Seattle saw a net increase of about 70% in the area of its tree canopy, showing that greenery has increased greatly in the city.


Trees


Next, we can look at individual trees planted in Seattle. The city is divided into its seven districts, with each district shaded in relation to it’s median household income - the darker the color, the higher the median income. Each green dot represents one tree planted in each district.


Figure Three


Because, again, direct comparison is difficult using this map, I will provide a graph comparing the count of each tree planted in each of the seven districts.


Figure Four


This graph seems to both confirm and dispute my hypothesis that the higher the district’s median household income, the more greenery there will be. According to the map, the two districts with the highest median income are Districts Six and Seven respectively, and the graph shows those districts as having the most amount of trees planted respectively. However, the two districts with the lowest median income according to the map are Districts Two and One respectively, which have roughly the same number of planted trees as Districts Three and Four. The district with the lowest number of trees planted by far is District Five, which ranks the third lowest for median household income.


Parks


Finally, we can look at the distribution of Seattle’s parks. Seattle is known for having beautiful parks, and as you can see in this spatial chart, some of the most common amenities in it’s almost 500 parks are nature-related.


Figure Five


Some of the most common are nature viewing areas, paths, waterfronts, woods and gardens. To see the distribution of these parks, I mapped each park and greenspace, represented by green polygons. I also included the location of Seattle’s environmental education centers, shown by teal circles.


Figure Six


This map shows no clear correlation between median household income and green spaces and environmental centers in Seattle. Additionally, it is impossible to accurately count the number of parks in each district because many parks stretch into two or even three districts simultaneously.


Conclusion

I was unable to prove my hypothesis that Seattle’s wealthiest districts are greener than it’s poorest districts. In figures three and four, you can see that, despite the two districts with the highest median household income having the most trees planted, the two districts with the fewest trees planted were not the ones with the lowest median household income. Furthermore, in figure six, it is evident that there is no pattern to the dispersal of parks across the different districts. The large vacant space in District 2 bordering Elliot Bay can be explained because that is downtown Seattle, where there is the highest density of buildings in the city. But this still does not appear to have a noticeable impact on the number of parks in District 2 compared to the other districts, as downtown is surrounded by many smaller parks. Finally, I think the locations of Seattle’s environmental education centers, which include the Seattle Aquarium, campgrounds and public beaches, show a concerted effort to diffuse green spaces and environmental amenities around the city, regardless of an area’s capital.

Though my hypothesis failed, I would argue the implications of this are far more positive than if my hypothesis had succeeded. Based on these maps, it seems that Seattle residents can access parks and green spaces no matter the affluence of their area, which has only positive physical and mental health benefits. Hopefully, Seattle residents take full advantage of this accessibility - on the few days of the year it isn’t raining, that is.


Sources


Images:

Seattle Park