FORTUNE — Ex-Googler and self-proclaimed “map geek” Eric Fischer has done some stunning work over the years extracting socioeconomic patterns from Internet data, including the Geotaggers World Atlas and Locals and Tourists, which was featured in the Museum of Modern Art’s 2010 “Talk to Me” exhibition.
But Fischer’s latest project goes one step further.
First he figured out how to map the metadata in 280 million Tweets sent since 2011 to reveal not just from where the messages were sent but also on what mobile platform.
Emily Badger at The Atlantic has posted maps of five U.S. cities (Atlanta, Chicago, Houston, Los Angeles, New York, Washington) created with Fischer’s mapping engine that show what seems to be a stark socio-economic-device divide, where the rich use Apple’s (AAPL) iPhones, and the poor use Google (GOOG) Androids.
But given that the gross national products of the U.K. and Spain are not so far apart, that doesn’t quite explain the map above, where one is painted Apple red and the other mostly Google green. Any theories?
Link to Fischer’s tool: Mobile Devices + Twitter Use