Check out this short film that illuminates the barriers between communities of people by tracking the movements of dollar bills.

Last year Northwestern University students created a mobility map of the United States by tracking individual pieces of paper money. They used the site Where's George, which allows people to enter serial numbers on bills, and creates a record of how those bills move from place to place.

The students, Christian Thiemann and Daniel Grady, placed first in the 2009 International Science and Engineering Visualization Challenge for the video.

Via Northwestern University.