With 500 million users, Facebook has grown as big as the population of the European Union. With so much potential data, Paul Butler, an intern at Facebook, decided to map out at least one aspect: the locality of friendship. "I was interested in seeing how geography and political borders affected where people lived relative to their friends," he explains. The result is a stunning map of the world, where rather than marking a coast or river or politcal border, each line signifies a real human relationship.
