Near the top of reasons to eat local is the impact such habits can have on the earth. As the treehuggers at Treehugger.com say:
Buying seasonal, local food is a boon for the environment for a lot of reasons. Since most food travels many miles to reach your table (1,500 miles, on average), locally sourced food cuts back on the climate-change impacts of transportation. Local food also generally uses less packaging, is fresher and tastier, and comes in more varieties. It also supports small local growers and lets them get more for their produce by not having to spend so much on packing, processing, refrigeration, marketing, and shipping. The best way to track down local food is at farmers markets or through community supported agriculture (CSA), which often offer home delivery.
Pretty much sez it all.