You may have seen earlier this summer a series of maps released by Twitter showing the geography of different cities as revealed by millions of tweets. Such maps of digital information are compelling for the way they also illustrate concrete infrastructure: the road networks around cities, the public parks inside of them, the clusters of commercial office buildings.
Maps of geo-tagged tweets always represent a biased sample of a biased sample. Tons of people aren't on Twitter. And of those who are, the vast majority never opt in to sharing their geographic location. The 275 million tweets shown in Mislove's map, collected between 2011 and April of the year, reflect just the 1.5 percent of messages that are readily geo-tagged. Still, these people appear to give a pretty impressive snapshot of the transportation networks of large stretches of the globe.
"The fact that you can see roads for example," Mislove says, "took me completely by surprise." Here, for example, are interstates 20, 85 and 75 converging on Atlanta:
We've embedded Mislove's full map below. But here are some of our favorite less obvious pieces of transportation infrastructure that clearly emerge from millions of tweets. On this map of the English Channel, you can see ferry boats crossing between Dover and Calais, on the French side:
A similar stretch of ferries run between Holyhead in the U.K. and Dublin:
And here ferries fan out from Istanbul in the Sea of Marmara:
In the San Francisco Bay Area, the Golden Gate Bridge, Bay Bridge, San Mateo Bridge and Dumbarton Bridge are all apparent:
If you find your own examples here – people waiting at airports? riding Amtrak? – please share them in the comments section.
All images courtesy of Alan Mislove.