Double a city’s population, and its economic productivity goes up 130 percent. MIT researchers think they know why.

In 2010, in the journal Nature, a pair of physicists at the Santa Fe Institute showed that when the population of a city doubles, economic productivity goes up by an average of 130 percent. Not only does total productivity increase with increased population, but so does per-capita productivity.

In the latest issue of Nature Communications, researchers from the MIT Media Laboratory’s Human Dynamics Lab propose a new explanation for that “superlinear scaling”: Increases in urban population density give residents greater opportunity for face-to-face interaction.

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