Geographic Mobility Neighborhoods

I was planning to do a review of the brain drain policy literature today, but got sidetracked researching a staff pick from the most recent State Science & Technology Institute Weekly Digest. From Northwestern University:

Thiemann and Grady produced their “Follow the Money” video to explain their project and animate the results. Tiny bills stretch out from county to county on a map of the contiguous United States. Some places, such as Los Angeles have many bills passing through it from across the nation, while others, such as Anderson County in Tennessee -- Grady’s home -- have bills circulating mainly within a more local neighborhood.

From this travel data, the team ran computer algorithms to find what they call effective communities within the United States. People tend to travel more within these invisible boundaries than outside them. In the video, counties flash and wiggle as the computer algorithm tries to decide which counties belong in the right community.

“Normally, you just push a button and wait for two hours and then all you get are numbers, which is really boring,” Thiemann said. “But [the animation] makes the process visible and shows you how interesting it can be.”

Grady hopes the video will stimulate other people to think up new ideas about what to do with these data. They’ve already started using it to study how diseases, such as H1N1, spread, and linguistics professors want to compare these travel boundaries to dialect boundaries.

I'm interested in mapping regional domestic migration connectivity. People connect places through geographic mobility. I've been struggling to figure out how to best quantify such connectivty profiles. You can view the video via the link provided above and see for yourself how this could be done.

At 3:42, there's a map of regions outlining "mobility neighborhoods". Like any contiguous geographic area, the boundaries are dynamic. However, we are able to abstract functioning units that we can understand as a community. I can see the Three Rust Belts that divide John Austin's Great Lakes megaregion.

I think this research could be used to rewrite US regional geography textbooks, as well as offer food for thought in economic development circles. At 4:02 in the video, one can see the more significant divisions. As usual, the map generates great research questions.

The data for dollar bill movements are tracked at the county level. So, each county and MSA will have a unique connectivity profile. We could look at the influence of Chicago and then trace that regional impact. It might be an interesting tool for evaluating geographic mobility programs such as Moving to Opportunity (Section 8 vouchers in Chicago). I'd like to use it to map domestic diasporas and zero in on strong inmigration opportunities for Rust Belt cities.

Watch the video yourself and imagine what you could do with the data.