Thursday, July 12, 2018

Mapping Seattle Population Density

The City of Seattle has grown tremendously over the past thirty years, and has added 114,000 residents just since 2010 (an increase of nearly 20%). This rapid population growth has resulted in a corresponding rapid increase in the cost of housing and the proliferation of construction projects to try to meet the demand. However, as a result of Seattle's zoning policies and Urban Villages strategy, this population growth (and the resulting changes to neighborhoods) has not been evenly distributed throughout the City.

We were asked by CAST Architects to model population density within the City of Seattle at three different time periods to get a better handle on where these changes are occurring. We mapped population density at the block level using US Census data for 1990  and 2010 and projected population in 2035 (taken from the City's Housing Affordability and Livability Mandatory Housing Affordability DEIS Alt 1).

Block groups are colored by density and displayed in three oblique views with the observer positioned southwest of the city, looking north/northeast. The maps show that the vast majority of the City's population growth has occurred in just a handful of neighborhoods--just 7% of the City's land area has absorbed 77% of all the growth!

Matt Hutchins at CAST continues to be a tireless advocate for increasing the construction of Detached Accessory Dwelling Units throughout the City, and used these maps in his presentation to YimbyTown to make the case that Seattle should expand housing options throughout the entire City, not just in the designated Urban Villages. 
Population density by block in 1990
Population density by block in 2010
Projected population density by block in 2035

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