From Fast Co.Exist
Theoretical physicist Dirk Brockmann was doing research on human mobility in 2005, but struggled to find good data until a friend mentioned wheresgeorge.com as a data source.
You can think of WheresGeorge.com as a primitive FourSquare for $1 bills. “Georgers”–as users call themselves–“check in” their bills by entering the zip codes and serial numbers, then write or stamp “wheresgeorge.com” on the bill. If someone finds the bill and enters it again, they get a “hit.” The top Georger–an ammunition dealer who goes by the handle Wattsburg Gary–has entered more than 2 million bills and has nearly half a million hits.
The resulting map shows how “effective communities” don’t necessarily follow state lines. “I don’t know so much about the culture of the U.S.,” says Brockmann