Laura Bliss is a staff writer at CityLab, covering transportation and technology. She also authors MapLab, a biweekly newsletter about maps (subscribe here). Her work has appeared in the New York Times, The Atlantic, Los Angeles magazine, and beyond.
A world map made of millions of geotagged tweets show the spots where locals—and tourists—flock.
Data artist Eric Fischer creates gorgeous maps of human movement across cities by plotting the social media trails of the world's denizens. Among other projects for Mapbox, where he currently works, Fischer recently released "Locals & Tourists," a searchable world map that visualizes the tweets of city residents versus out-of-towners. Using Gnip's archive of geo-tagged tweets from September 2011 through May 2013, Fischer designated "locals" as those who'd been tweeting from the same city region for one month or longer. Their tweets are blue spots on the map. "Tourists" (red spots) were those who'd been tweeting in that city for less than a month, and who seem to be "locals" in another city.
Remarkably, the tweet-points are not overlaid onto an existing world map; rather, they manifest into recognizable urban geographies. This becomes apparent when you zoom in tight or all the way out: neighborhood, county, and national boundaries simply aren't there. In these maps, the world is a sum of its tweets.
In a way, "Tourists & Locals" updates an older project of Fischer's, where he mapped tourists and locals in than 130 international cities using geo-tagged Flickr photos. In those maps, blue dots are locals, red dots tourists, and yellow dots are those who Fischer couldn't determine.
Looking back, Fischer compares how the different data sources affect the distribution of residents and visitors across cities. With the Flickr-based series, Fischer says "there were cities like Las Vegas and Venice with almost no photos posted outside of the areas where tourists go, challenging my expectation that every city would have places that were meaningful to locals but that tourists don't know about." The tweet-based map, meanwhile, is "probably more representative of a broader slice of life and of local neighborhood concentrations."