Definitions of "local"
The definition of "local" or "regional" has for a long time been flexible and defined differently depending on the person in question. Neither the USDA nor any legal authority has adopted a definition.
Some local business with specific retail and production focuses, such as cheese, may take a larger view of what is 'local' while a local farm may see the area with in a day's driving as local because it is a reasonable distance to transport goods and services—in fact, 400 miles is essentially a DGD (day-goods-distance). Some see "local" as being a very small area (typically, the size of a city and its surroundings), others suggest the ecoregion or bioregion size, while others refer to the borders of their nation or state. The concept of "locally-processed" however has recently been introduced by the produce industry including organic produce wholesalers and retailers. This is potentially a dubious concept as it appears to be an excuse to ship across country and re-package in order to retain the "local" definition. This would enable huge processors to retain a local edge theoretically anywhere on the planet.
Some proponents of "local food" consider that the term "local" has little to do with distance or with the size of a "local" area. For example, some see the American state of Texas as being "local", although it is much larger than some European countries. In this case, transporting a food product across Texas could involve a longer distance than that between northern and southern European countries. It is also argued that national borders should not be used to define what is local. For example, a cheese produced in Alsace (France) is likely to be more "local" to German people in Frankfurt, than to French people in Marseille.
The concept of "local" is also seen in terms of ecology, where food production is considered from the perspective of a basic ecological unit defined by its climate, soil, watershed, species and local agrisystems, a unit also called an ecoregion or a foodshed. The concept of the foodshed is similar to that of a watershed; it is an area where food is grown and eaten. The size of the foodshed varies depending on the availability of year round foods and the variety of foods grown and processed. In a way, replacing the term 'water' with 'food' reconnects food with nature. "The term "foodshed" thus becomes a unifying and organizing metaphor for conceptual development that starts from a premise of the unity of place and people, of nature and society." 
Where local food is determined by the distance it has traveled, the wholesale distribution system can confuse the calculations. Fresh food that is grown very near to where it will be purchased, may still travel hundreds of miles out of the area through the industrial system before arriving back at a local store. This is seen as a labeling issue by local food advocates, who suggest that, at least in the case of fresh food, consumers should be able to see exactly how far each food item has traveled.
IMO, I think local is if it was grown in the same county as you.