The most recent study in Andersonville, Illinois in October, 2004 evaluated the economic role played
The most recent study in Andersonville, Illinois in October, 2004 evaluated the economic role played by the independent businesses and the results showed that for very $100 in consumer spending with a local firm, $68 remains in the Chicago economy vs. $43 for spending at a chain store. (CITE) [ie. About 50% more stays local]
Source: Growing Local Value by Laury Hammel