Another road-themed piece today, this time looking at US Interstates, and how many people live in between them. Why? Curiosity, plus it's a nice little data challenge using Census block population data from 2020. First off, let's start with the Beltway around Washington, D.C. - using 2020 Census data I get a total population of just under 2 million people (1,961,212), as you can see below.
|Web map of the whole US is here
This is what the web map looks like.
|Click an area to get the population
I loaded up a MapTiler streets backdrop layer in QGIS, created polygons from the the US national road network file from the Department of Transportation website (this required a lot of error checking/fixing) and then summed the population of all areas bounded by Interstates - including those in Hawaii, Alaska and Puerto Rico.
Some numbers to begin with:
- 82 million people live entirely unbounded by Interstates (25% of the total - in the big red area in the map below).
- 10.4 million people live in the most populous 'bounded by Interstates' area.
- The next most populous bounded area has 5.6 million people in it (it's in Florida, see below).
- There are 83 'bounded by Interstates' areas with more than 1 million people.
- I get 443 populated bounded areas plus one 'at large' area, unbounded by Interstates.
- There are bounded areas in Alaska, Hawaii and Puerto Rico as well as in the lower 48 states - see the web map for those.
- A few areas have fewer than 100 people in them - a couple of these seem to be statistical quirks (e.g. mismatched boundaries) but many are real, including this bounded triangle in Chicago.
|Such vital research
Okay, show me the maps
|Central Florida (second highest intrastate population)
|Washington, D.C. (The Beltway)
|Another Atlanta (different resolution)
|The only bounded area of Phoenix
|San Francisco Bay Area
|The Inland Empire (CA)
|Cleveland - so much boundedness!
|Salt Lake City
Where are the furthest places from an Interstate in the lower 48?
|Furthest from an Interstate
How about those tiny areas bounded by Interstates?
|Somewhat hemmed in
|Actually pretty leafy here
|Also pretty leafy here too
|Downtown apartments in St. Louis?
|West Bottom Flats, etc
|This one's mostly empty space
|Fairly unexciting here
|A very interesting little chunk of space (street view)
|Another Anchorage, AK one
|The oldest/fuzziest street view imagery in the US?
|People definitely live here, but not many
|Yeah, this is just an anomaly
|Another weird anomaly
|I think it's just trucks and truckers here
|Yeah, no. But two Census blocks fit perfectly in here, so hmm