A few months ago, some people in Cambridge, MA were inspired by the example of Todmorden in the UK between Leeds and Manchester, a town that decided to grow as much of its food as possible within the town limits.
Since we started meeting, some of us have begun mapping the Cambridge local food system which already exists. It includes farmers' markets every day of the week from Memorial Day to Thanksgiving, the local growing season, and one winter market on Saturday mornings. There are City Sprouts (http://www.citysprouts.org/) gardens in every one of the 12 public middle schools, 15 community gardens including those at Harvard and Leslie Universities, and at least three restaurants with rooftop or container gardens. Local organizations include Pick a Pocket Garden (http://pickapocketgarden.org/) which is planting and maintaining public plantings of ornamentals, a yogurt-making coop, and the League of Urban Canners who will harvest and process fruit from neighborhood trees and bushes into preserves, with the owners getting 10% of the product.
The Cambridge Todmorden group may have access to three different sites for public gardens but we haven't turned any soil over yet, although we certainly plan to in the near future.
A few schools, community plots, and restaurants will not grow any appreciable percentage of the food in Cambridge, MA but it is a start. There is a local food system. We are learning how to grow it.
Todmorden has a population around 15,000. Cambridge has a population of about 100,000. The Todmorden example may not be completely applicable to Cambridge let alone cities of larger scale. However, Linköping, Sweden, a city of about 104,000 people is considering a vertical farm project to become self-sufficient in food (http://www.good.is/post/a-vertical-greenhouse-could-make-a-swedish-city-self-sufficient/) while Chicago is already building their first vertical farm (http://www.plantchicago.com/) and Berlin is planning the world's largest rooftop fish and vegetable garden (http://www.treehugger.com/sustainable-agriculture/worlds-largest-rooftop-fish-and-vegetable-farm-pla nned-berlin.html).
In the US, Growing Power (http://www.growingpower.org/) in Milwaukee is probably the most successful urban gardening project. Today, 1% of the food consumed in Milwaukee is grown in the city but Growing Power wants to increase it to 10% within two years. They plan to build 100 acres of greenhouses for year-round growing and have begun a 20,000 backyard garden program. You can see their founder, Will Allen, talk about their work on CSPAN's Book TV (http://www.booktv.org/Program/13443/The+Good+Food+Revolution+Growing+Healthy+Food+People+and+Communi ties.aspx)
There's even a feature length documentary on this nation-wide movement entitled "Edible City":
Locally, Cambridge is not alone in discussing these issues. Boston, MA has been meeting for most of the year to develop a plan for urban farms, and Concord, MA has just finished a community food assessment, "Building Local Food Connections" (http://issuu.com/conwaydesign/docs/concordfood2012).
Here are a couple of upcoming web-based events that will teach you more about local food systems:
Tips, Tools and Telling the Story: Evaluating Community Food Initiatives
Food Systems Networks That Work: Accelerating Learning and Increasing Commerce NGFN Interactive Webinar
Learn how joining or fostering a food hub or food system network can improve your regional food economy and the strength of each member organization or business. This webinar will feature conveners of food systems networks at the local, state, regional, and even national level. The networks they've built have boosted triple bottom lines of member businesses and organizations.
Local Food Network: Cambridge, MA
Integrated Urban Agricultural Systems
How to Heal the World
Urban Fruit Harvesting
Community Gardens as Permaculture Nurseries
Growing Green in the City
Celebrate Gleaning with the Boston Area Farm Gleaning Project
Urban Permaculture: Chicken Coop Grapevine and Water Footprint
How Cuba Survived Peak Oil