By the Numbers: Food Miles

1,500 miles. That’s the average number of miles it reportedly takes for your dinner to get from the farm to your table. Featured in Newsweek, TIME Magazine and The New York Times, this number has contributed to a growing local eating movement. Sales of locally grown foods are expected to reach $7 billion this year, up from $4 billion in 2002.

The number originated from a study called “Food, Fuel, and Freeways” conducted in 2001 by Rich Pirog, associate director at Iowa State University’s Leopold Center for Sustainable Agriculture. Pirog wanted to quantify how many miles it took 28 fruits and vegetables to reach the upper Midwest by truck. The number averaged close to 1,500 miles. When he did the study again in 2003, the results were largely the same. But Pirog had no idea he was generating what he calls a “magical number.” In fact, he was surprised his study’s results were coined for the masses, since they were so specific regarding food type and location. “We never expected the small food miles studies looking at fresh produce coming into the upper Midwest by truck to generate so much buzz. The average distance we calculated took on a life of its own and was often cited incorrectly as the average distance food traveled in the United States,” Pirog says.

According to the U.S. Department of Agriculture, there are many factors that determine whether a food item is environmentally friendly. Transportation is near the bottom of the list. Pirog himself noted that food miles are a great indicator of how local a product is, but not how environmentally friendly it is. In order to shrink the fossil fuel in our diets, what we eat is more important than where it’s from.

In a 2008 study, Christopher L. Weber and H. Scott Matthews of Carnegie Mellon University found that transportation accounts for just 11% of the greenhouse gas emissions of fruits and vegetables and only 1% of red meat’s emissions. How the food is produced contributes a whopping 83%. Reducing meat consumption, in other words, is far more eco-friendly than switching to locally grown tomatoes. In fact, the study reports, by switching from red meat and dairy products to chicken, fish, eggs or a vegetable-based diet less than one day a week, you achieve more greenhouse gas emissions reduction than you would by buying all locally sourced food. And Weber points out that “It’s much easier to shift one day of my beef consumption a week to chicken or vegetables than to eat only Jerusalem artichokes for three months in the winter.”

That doesn’t mean eating locally doesn’t have its place. Local food builds community, poses a smaller risk for food-borne contaminants and tastes a lot better. It doesn’t require the refrigeration needed for long-distance hauling, and is often free from packaging waste. But it’s no replacement, environmentally speaking, for eating lower on the food chain.