Cellphone Data Track Our Migration Patterns

Cellphone users are spiders of the electromagnetic spectrum, spinning intricate, invisible threads of data about themselves as they walk and talk throughout the day.

Physicists, urban planners and social scientists are eagerly weaving millions of these electronic threads into patterns of people on the move, through studies that until now were all but impossible.

Unable to track human migrations accurately, researchers investigating travel had to make do with indirect measures of mobility. For example, they monitored the movement of bank notes from person to person through online sites such as the United States Currency Tracking Project's Where's George?

That's rapidly ...