I am by no means some sort of hippie localvore vegan guy, but I am finally coming around to realize that it does matter at least a little.
Living in Chicago, we are basically local vegetable free for most of the year, so there is no way I am going to only eat local all winter. I don't have a root cellar, and I'm not really into canning, so come November I'm going to buy the California or South American produce. Have you noticed how most of the localvore people come from California, where you can pretty much get every vegetable year round?
That being said, it does matter where you get your food from when you have choices. This summer, I am trying to stick with local (Illinois, Indiana, Wisconsin or Michigan) grown fruit and vegetables. You'll now see me every Saturday at the Green City Market in Lincoln Park. This time of year I'd rather pay a little more to help out local farmers, rather than to buy corporate-farm food from someplace far away.
Where the far away food really worries me is seafood. I was at Trader Joe's yesterday, and all of their seafood came from the Philippines, Singapore or Hong Kong. I have no idea what farm raised scallops or shrimp eat in the Philippines. Even at the foodie bastion of Whole Foods, I had a hard time finding seafood not sourced from the far east. They had one bag of frozen shrimp from US, and it was, not surprisingly, much more expensive than the foreign shrimp. It was very good, though. After the BP mess in the gulf, I'm trying to buy more US seafood to do what I can to keep the fishermen and shrimpers in business.
Anthony Bourdain's new book Medium Raw was an eye opener in regards to one of my other favorite things, the hamburger. Low grade hamburger can include all sorts of bad stuff. Thanks to him, I now am a little wary of eating burgers in cheap restaurants. Ammonia cured burger meat isn't very appetizing. So I've started skipping the burger at the more divey places I go for lunch. Don't worry, I'm not getting healthy food, but I'm picking things I trust more, like Vienna Beef hotdogs or Italian beef sandwiches.
As an aside, Medium Raw is a great book. I loved the Audible version, it's like a 9 hour long uncensored episode of No Reservations.
I'm not sure what to do in restaurants in regards to seafood & meat.
The waitstaff have no clue in many places where their food comes from and I can't afford to only eat in places that only buy from 'name' local producers. For an example of that, check out the menu at The Publican, one of my favorite restaurants. For now, I'm probably not buying burgers and shrimp from most chain places, and I'll be a little more careful with other seafood. There's nothing wrong with eating more steak :)