There's just one small problem: winter. For those of us in temperate or northern climates, a local diet would be seriously vitamin-deficient -- not to mention boring -- for four to six months of the year. As a South Dakota resident colorfully put it:
If all I bought was local production in the wintertime, I wouldn't be buying anything but meat. I would have the same vitamin-deficient, fruit-deficient, vegetable-deficient diet that people had in the 1800s, when they lived on bread, beans, bacon, and potatoes for 6 months out of the year, and died in their 50s. A flu germ would kill me. If you want vitamin C, you're gonna have to import.So, is there a way out of this dilemma? Yes, and its name is passive solar design. In one incarnation, described by Tom Philpott in Grist Magazine, this involves combining greenhouses built right into hills with using large barrels of water to store up heat. Another version, which even works in Maine, uses cold frames and varies crops with the seasons. Almost certainly, other possibilities exist that haven't been invented yet.
I do not think it is necessary or desirable to rely entirely on local produce, but it should certainly become more common than it is. (Why is Florida orange juice so common in California? What are California peaches doing here in Georgia?) The big lesson of passive solar design in agriculture is that we shouldn't automatically accept trade-offs between truly desirable things. Very often, we can have our fresh tomatoes and eat them, too.