Where’s George? is a project tracking one dollar notes in the US. Put a stamp on the note, and log it on the website. Creates link between the two places where the not was logged. Provides a lot of data about how money moves around the US, therefore data about how people move around the US.

Administrative system of US: Divisions contain States contain Counties. Spatially compact hierarchical structure historically evolved with geographic determinants.

Human mobility – are these divisions spatially compact, determined by geography? How much geography is encoded in the network of money movements?

Can make groups of counties, run algorithms to test the strength of borders between devisions/states/counties. Shows Mississippi River is a strong border, as is Colorado/Ohio border.

Compare to epidemiology, SIR model – susceptible, infectious, recovered, i.e. what happens when an infectious person meets a susceptible person, etc. No spatial element in this model. When modelled, see a wave of infection moving through the world.

But modern transportation, aviation, changes it. Incorporate that, creates new model of spread of disease worldwide, e.g. SARS. Modelling based on country doesn’t provide enough granularity. Using Where’s George? data, can see how people move around the US.

No dataset like WG. Local travel data and aviation data, but doesn’t show full picture.

Nw model for Swine Flu, combine WG data with for spread, and show where possible flu hotspots might be, e.g. LA, Dallas, Miami, Chicago, NY areas.

Can look at multiscale mobility and local mobility, they show very different spreads of disease.