I am just starting down this path of learning exactly where my food is grown or where it comes from. I have been avoiding fast food for many years and most processed foods for almost as long, but it has been a drastic change from how I was raised and what I knew. It has been very gradual as my exposure has been broadened in gentle ways. I suggest a heavy dose of kindness in discussing these issues with folks.

Meanwhile, another few good resources (in addition to the above-mentioned):
Stuffed and Starved by Raj Patel - available at libraries
Fatland by Greg Critser - available in libraries
The Real Dirt on Farmer John - available on netflix
Good Food - I saw this at a local lecture series, but I don't know how just anyone could view it. It is excellent specifically because it shows how small farms are creating entire communities of healthy food in Washington and Oregon (from sustainable growing to restaurants to farmer's markets to grocery stores and so on).
Since urban areas were discussed a few times in this thread as potentially not viable locations for supporting these concepts, I thought I would share some great things happening in my urban area (San Diego - very large city located in basically a desert by the ocean).
~ We have a number of colleges in this city and many of them are now growing food on campus and selling it directly to students and the general public through farm stands and farmer's markets. City College and UC San Diego have been doing it for awhile, but I recently learned of a handful more and, additionally, others who are just getting started. This is excellent for many reasons, but the most compelling is we need young people to take an interest in their food because they are the future of our country. Like it or not, change is often a slow process.
~ And not just colleges, but my DD's elementary school has had a school garden for 2-3 years now and we got the idea from other elementary schools in town. At this age, obviously the focus is a bit different but it is the beginning of the education process.
~ One of the local churches (a half-mile from my house) has a large community garden and they feed homeless people with the produce along with having a few plots for families without gardening spaces to grow some food.
~ On a larger scale, we have several large communities who have banded together to grow food and sell it through local farmer's markets in their low economic neighborhoods. This is particularly important due to the social injustices for low income families and (limited) access to healthy food.
~ Like other places, we have CSAs and co-ops, too. I recently discovered a pastured meat CSA that has drop-offs in our city. We are also getting old-fashioned butcher shops back (slowly).
~ A local news weatherman has a real passion for sustainable agriculture and he has written at least one book and is spearheading a local movement to educate the public on these issues. I'm attending a year-long lecture series titled
Sustainable Planet: Food that is drawing hundreds of people every single month and the speakers are coming from all over the world with a common theme: local, sustainable food systems can and do exist.... with the underlying theme that we need to take political action to ensure they can continue in this country and, more importantly, so that we can change the current food system in order to enable more of these sustainable systems to come about. It is a rather daunting prospect in many ways when one is presented with all the legal obstacles thrown in the path by large corporations controlling both ends of the current food system (farmers through seed control etc and consumers through marketing and supermarket choices) and paying large amounts of money to government to keep things the way they are.
From what I have read, our current food system started not because of greed (at least not from the same corporations that are exhibiting it now) but because of out of control food prices back in the 70s due to the oil crisis. The government needed a way to provide cheaper food for Americans and the folks in power back then acted quickly without thinking through the full ramifications of their policies. Going a bit further back, though, the end of WWII left a lot of empty facilities and unemployed people, which started this country down the industrial revolution path. Food was no exception. It has been a slow and insidious change with a few landmark actions and has snowballed into the highly polluting mess that it is today. Polluting in many ways: health and environment and social and so on....