Earlier last week, the New York times published "The Hot Spots for Organic Food" in which they provided maps of farms in the United States. The data was compiled for the 2007 agricultural census.
I've published the map of all vegetable farms, as a vegan that is the most interesting to me. The rest of the short article has maps of all farms, the organic farms, orchards, and dairy farms. It's an interesting look at where our food comes from. You may even be surprized.