Update [2007-8-24 9:4:33 by Tom Philpott]: Now this is really getting vexed. As Gristmill blogger JMG comments below, the Department of Energy did not exist in 1969. (Jimmy Carter started it in ’77.) Hmmm. Rich Pirog of the Leopold Center, mentioned below the fold, emailed me with his source on the 1969 study: a paper by John Hendrickson, naming the Department of Energy as the source. Rich is going to try to get to the bottom of this annoying mix-up. Meanwhile, I’m going to try to get my hands on the paper, regardless of which bureaucracy produced it.

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In Fork it Over, I (attempt to) answer questions inspired by my Victual Reality column. Got a question about food and the politics that surround it? Fork it over, by emailing it to victuals(at)grist(dot)org.

food miles

Responding to my recent column "The Eat-Local Backlash," reader Steven Schnell of Kutztown, PA writes in to ask: “I have long been perplexed as to the source of the oft-quoted figure for average food miles of 1200 miles (or sometimes 1500 miles). Every food writer in America quotes it. But nobody ever gives a citation. Do you have a specific name/reference for this study? I’d be eternally grateful if you did!”

Such a straightforward question. If only the answer could be straightforward, too!

First, a mea culpa. My piece on the eat-local backlash contains the following sentence: “Way back in 1969, the U.S. Department of Defense performed what remains the only comprehensive nationwide study of the average distance food travels from farm to plate. The study’s estimate, 1,200 miles, probably falls well short of the current mark."

A wit once remarked that the Holy Roman Empire was neither holy, nor Roman, nor an Empire. My statement has proven similarly flawed.

For one thing, the much-cited DoD report may well not exist. But a 1969 study of food miles by another government agency — the Department of Energy — does, and it puts the number at 1,346 food miles, not 1200.

Ouch. However, my claim that the number "probably falls well short of the current mark" does seem to stand, as I’ll explain in a bit.

I have no idea how my brain downgraded the estimate to 1,200 miles, but I do know where I got the DoD bit from. The existence of a 1969 food-miles study by the DoD has been floating around for a while. It appears in an excellent 2002 paper by researchers at the Johns Hopkins Center for a Livable Future: "How Sustainable Agriculture Can Address the Environmental and Human Health Harms of Industrial Agriculture" (PDF). The paper contains this sentence: "A 1969 study by the Department of Defense estimated that the average processed food item produced in the United States travels 1,300 miles before it reaches consumers."

Hmmm. The footnote for the sentence leads not to a citation of the study itself, but rather an out-of-print 1981 book from Rodale Press called Empty Breadbasket? The Coming Challenge to America’s Food Supply and What We Can Do About It: A Study of the U.S. Food System.

I’m going to try to dig up that book at the library, and I have a call into the authors of the Johns Hopkins study. If they call after I post this, I’ll report on the conversation in comments.

So how did I figure out that the real source for the 1969 study was the DoE, not the DoD? I called Rich Pirog of the Leopold Center for Sustainable Agriculture, who probably counts as our most rigorous and careful source of info on food miles.

Rich did a comprehensive look at food-mile studies for his 2001 paper "Food, Fuel, Freeways: An Iowa perspective on how far food travels, food usage, and greenhouse gas emissions."

The only study he knows about that comprehensively estimates food miles nationwide is the 1969 DoE effort. Reader Steven, if you’re still with me, the citation for it is: U.S. Department of Energy. 1969. "U.S. Agriculture: Potential Vulnerabilities." Stanford Research, Institute, Menlo Park, CA.

I’m still trying to get my hands on it. Pirog says the study covers processed food, nationwide. He says average food miles have definitely grown since 1969. Since then, the food industry has consolidated dramatically, meaning far fewer small-scale processing facilities, and food imports have exploded.

Pirog himself has studied food miles on fresh produce — not processed food, as in the DoE paper — coming into the Chicago terminal market, where it is then distributed throughout the upper Midwest.

On page 13 of his above-linked paper, we find that:

In 1981, produce traveled an average of 1,245 miles by truck from locations within the continental United States to reach the Chicago terminal market. The average distance for produce arriving by truck in the continental United States increased to 1,424 miles in 1989, and to 1,518 miles in 1998. The 1998 estimate is a 22 percent increase in distance over the 1981 figure.

Note well: this can’t be compared directly to the DoE study, because it focuses on one region, rather than the whole country, and it looks at fresh produce, not processed food.

On page 9 of the same paper, Pirog does a mini lit review of other studies, each footnoted. Again, all of them are regional, and deal with produce.

Calculations made by John Hendrickson using a 1980 study examining transportation and fuel requirements estimated that fresh produce in the United States traveled an estimated 1,500 miles. Fresh produce arriving in Austin, Texas, was estimated to travel an average of 1,129 miles. An analysis of the USDA Agricultural Marketing Service’s 1997 arrival data from the Jessup, Maryland, terminal market found that the average pound of produce distributed at the facility traveled more than 1,685 miles. This same study showed the average distance for fruits to be transported was 2,146 miles, while the average for vegetables was 1,596 miles.

What, then, can we conclude? We can say with confidence, I think, that our processed food travels at least an average of 1,346 miles, and our fresh produce in most regions of the country log between 1,500 and 2,000 miles on the road.

Anybody who has info on food miles not covered in this post, please comment.