There Are 1.75 Mil. People Inside the Beltway & Cool Maps
I noticed the Inside the Beltway geography is often not explored an isolation, so I’m here to provide some cocktail-hour conversation starters. People often show stats about the District of Columbia, but as an urbanist I tend to think of things in terms of the “functional city.” The Metropolitan Statistical Area is often one definition, and there are countless others, as to what a “functional city” means, but lets look at the DC functional city as Inside the Beltway.
I calculated some statistics for you, and here’s the main one you’re wondering about: there are 1.75 million people inside the Washington Beltway. I also made some interesting maps for you folks.
Method
By inside the beltway, I mean exactly that: the are inside the I-495 beltway that surrounds Washington, DC. This excludes areas like Tyson’s Corner (but not my neighborhood, Pimmit Hills, just inside the Beltway!), Reston, and parts East in Prince Georges County.
The way I did this was to get the Census Tract TIGER shapefiles from the US Census. I used the ArcGIS trace tool to only select the census tracts that are within the beltway. Finally, I tied this to 2011 ACS 5-year population estimates to get our statistics.
To calculate density, I had to calculate the land area. I got the total area, did some water shapefile manipulation (merge, clip, etc). Eventually subtracted out the water area, also using Census TIGER files. That way we know the land area.
And for those of you who keep score at home, for break points in the visualizations, I used 7 “natural breaks” categories for each of the maps.
Population Stats Overview
Again, I’m literal: Inside the Beltway. And here are the statistics for the Inside the Beltway area, and how it compares to other cities.
Population Map
(note: map doesn’t work on mobile browsers)
Click for Larger Map
By population, you can see that the area is rather dispersed throughout. This isn’t a big demographic analysis here, and I’m just giving you a nifty tool using ESRI Online maps. Take a look around, explore, and see some of the population trends.
Density Map
(note: map doesn’t work on mobile browsers)
Click for Larger Map
I’m anticipating people saying, “hey, Mike, what about density?” Well, here is that map too. As you see, we have strong density where you expect, especially along the 15th and 16th street corridors in DC, and in NW DC overall.
As far as some of the other standouts, we have the area around College Park, the Arlington / Clerndon Blvd. corridor, areas near Georgetown, and some more obvious spots.
Crowdsource project! Can some of you folks explain some of the more “random” standouts. I’m looking at you, area near Seminary Rd meets I-395!
Originally published at www.transpoplanner.com on March 17, 2013.
