Infographic: To Map Cross-Country Migration, Just Follow the Money

Using data culled from the web, an application reveals where we get our money--and where we spend it.

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Mapping migration patterns across America is harder than you think. Using airplane flight-data doesn't capture people's everyday travels. And you can't track everyone's everyday car movements (legally).

So Christian Thiemann and Daniel Grady of
Northwestern University found an alternative: the flow of dollar bills. Specifically, they used data culled from Where's George, a website you can...