"According to the definition adopted by the U.S. Congress in the 2008 Food, Conservation, and Energy Act, the total distance that a product can be transported and still be considered a 'locally or regionally produced agricultural food product” is less than 400 miles from its origin, or within the State in which it is produced.' Definitions based on market arrangements, including direct-to-consumer arrangements such as regional farmers’ markets, or direct-to-retail/foodservice arrangements such as farm sales to schools, are well-recognized categories." Given the definition of local food system described above, the local food system would focus on a much smaller geographic area than a 400 mile radius, perhaps 50 miles or less, but the actual distance would depend on the connections between a particular place and its surrounding food supply chains.
Source: USDA, Economic Research Service, Report # 97, May 2010. http://www.ers.usda.gov/Publications/ERR97/ERR97_ReportSummary.pdf
Sometimes referred to as a community food system, "... a collaborative network that integrates sustainable food production, processing, distribution, consumption and waste management in order to enhance the environmental, economic and social health of a particular place." Source: Cooperative Extension System http://www.extension.org/pages/18378/food-systems-introduction