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Food System Primer

Food Distribution


Grain Train

Freight train carrying grain across Washington state.

“If the stupendous system of food preservation and transportation which supports us were interfered with … cities with thousands of inhabitants would fade away. We would probably turn into beasts in our frantic struggles to reach the source of supply.” – Golden Book Magazine, 1931.1

Photo credit: David Gubler. Creative Commons CC BY-SA 3.0.

Click images for captions

It is not extravagant to say that our present form of civilization is dependent upon refrigeration.

– Golden Book Magazine, 1931.1

Chilean grapes, Alaskan cod, Nebraskan beef, and nearly every vegetable grown under the California sun are at supermarket shoppers’ fingertips. The variety, abundance, and year-round availability of perishable foods are a modern marvel, made possible by the “cold chain”—an uninterrupted series of refrigerated vehicles and storage facilities that keep food within an ideal temperature range. Even before distributors began using mechanical refrigeration in the late 1800s, rail cars, steamships, and warehouses were cooled with ice to keep food from spoiling over long journeys from producers to consumers. Today, the cold chain allows perishable food to be transported to and from all corners of the globe.1

When international food imports first entered U.S. markets, they were all the rage. In the 1930s, one upscale New York restaurant chain boasted on its menu about the mileage traveled by its exotic produce. The ingredients in their vegetable salad, they claimed, had traveled a cumulative 22,250 miles.1    

Today, restaurants are more likely to take pride in local ingredients. Consumers are paying more attention to where their food comes from, partly out of concern over environmental impacts of long-distance transport. How far food travels, however, may not be as important as what people eat, how food is produced, and why it is transported long distances in the first place.

Why food is transported long distances


Wheat fields in the southern Great Plains.

Transporting food over long distances can allow a region’s farmers to focus on what they do best. The types of production best suited for a region depend on qualities like climate, topography, and soil. The cold, dry climate of the Great Plains, for example, is well-suited for growing the variety of wheat used in breads and baking.

Photo credit: Roy Kaltschmidt, Lawrence Berkeley National Laboratory. Creative Commons CC BY-NC-SA 2.0.


Inside a hoophouse at Real Food Farm, Baltimore.

In northern latitudes, most fresh food production is suspended through the winter, increasing reliance on food from warmer climates. Farmers can, however, trap the sun’s heat and extend the growing season by constructing a hoophouse, an inexpensive structure with a metal frame and a plastic insulating cover.

Photo credit: Brent Kim, Johns Hopkins Center for a Livable Future, 2009.


Canning (pictured) can help people in northern latitudes enjoy a nutritionally-diverse diet without relying on food from far-away places.

Photo credit: mlhradio, Flickr, 2009. Cropped from original. Creative Commons CC BY-NC 2.0.

Click images for captions

There are some valid reasons to transport food long distances, including:

Feeding densely populated areas: According to one estimate, if all the agricultural land in New York state were devoted to feeding New York City’s population of 8 million2, there would be only enough food to feed half  the city—with nothing left for the rest of the state.3 One adult eats roughly one ton of food per year. Where there are a lot of people in one place, there may not be enough local farmland to support them all.

Out-of-season variety: In northern latitudes, most food production is suspended through the cold season. If people in those regions ate only local food, their options would be very limited unless they preserve fruits and vegetables to last the winter. Some households are doing just that, but it requires effort and planning. Otherwise, shipping food from Florida, California, Central and South America, and other southern locales can provide people with year-round variety and nutritional diversity over the winter months.

Allowing regions to focus on their strengths: Some regions are better at producing certain foods than others. Vermont, for example, has a short growing season, rolling hills, and rocky soil—less than ideal conditions for growing many crops but suitable for raising dairy cows.4 From an economic standpoint, it makes sense for Vermont’s farmers to focus on the products they are best suited for. In fact, they produce far more milk and dairy products than are consumed within Vermont,5 and export the surplus to other states. Other states, in turn, export to Vermont the foods they are best at producing.

Other reasons have to do with the nature of the food distribution industry (see below).

Food distributors

Food distributors provide a bridge between the people who produce food and those who sell it. They gather products from farmers and food processors, store them in warehouses, and then transport them to retail and wholesale buyers.

Large businesses like supermarkets, chain restaurants, and food service providers for schools, hospitals, and other institutions rely on distributors to help acquire the many foods and ingredients they need to operate. A supermarket, for example, does not have time to purchase from hundreds of different farmers and processors to stock their shelves. One farmer, meanwhile, rarely produces enough food to make it worthwhile for a large business to purchase directly from them. A distributor brings together goods from many different producers and processors so they can be sold in bulk.

Food distributors are also part of the reason foods are transported long distances. Larger, more competitive distributors may buy only from large farms that provide a steady supply of goods at the lowest prices—even if those farms are halfway across the globe.6,7 This competition for lower prices can drive smaller farmers out of business, while making regions more dependent on food from faraway places. For example, in 1870, all the apples eaten in Iowa were grown by Iowa farmers; by 1999, 85 percent were imported from outside the state.8

Some smaller-scale farmers are getting around these problems by “cutting out the middleman” and selling directly to consumers (e.g., at farmers’ markets). Farmers get a larger share of the profit this way, and they can build personal relationships with consumers who want to know and trust where their food comes from.

Food miles


Left: Energy used to transport one ton of cargo one kilometer.10 Right: GHG emissions from transporting one ton of cargo 1,000 kilometers.10

Fossil fuel–powered vehicles deplete dwindling oil reserves, impact air quality, and emit greenhouse gases (GHGs) that contribute to climate change. By rail and by sea are generally the most energy-efficient modes of transport, though air freight can transport the most perishable items, such as strawberries and cherries, that would otherwise spoil over long, slow journeys.11

Data source: C. Weber and H. Matthews, 2008.10

GHG Supply chain

Greenhouse gas (GHG) emissions by stage of supply chain.

What people eat generally matters more for climate change than how far food travels. Across the U.S. food supply chain, from farm to retail, transportation accounts for only an estimated 11 percent of GHG emissions. Most emissions are from producing food, particularly animal products. Research suggests that if Americans followed a plant-based diet one day per week, they could cut GHG emissions more than by following an entirely local diet.9


In some cases, trading food with faraway places has advantages over eating local. According to one study, producing lamb and dairy products in New Zealand and shipping them to the United Kingdom used less energy, and produced fewer greenhouse gas emissions, than producing these foods in the U.K. This is mostly because the animals in New Zealand grazed on pasture year-round, whereas in the U.K. they were housed indoors and required feed.12

Photo credit: Phillip Capper, 2006. Creative Commons CC BY 2.0.

Click images for captions

For most of human history… perishable foods were by definition local.

– Susanne Freidberg, Fresh: A Perishable History1

The term “food miles” refers to the distance foods travel from where they are produced to where they are purchased or eaten. One study suggests fresh fruits and vegetables grown in the U.S. travel roughly 1,500 miles, on average, before they are sold.8

Food miles have come under scrutiny by conscientious consumers, often out of concern for public health and the environment. Fossil fuel–powered vehicles deplete dwindling oil reserves, impact air quality, and emit greenhouse gases (GHGs) that contribute to climate change. In some cases, purchasing locally produced foods may lessen these impacts by reducing transport distances.

Food routes, however, are rarely as simple as a straight line from farm to market. Processed food companies often source ingredients from multiple farms, and their products may be sold and re-sold through many distributors before arriving in stores. Meat, milk, and egg production usually involves shipping feed to animals and transporting animals between breeding, feeding, and slaughtering facilities. 

Some transport vehicles are also more efficient than others. Trains, for example, are many times more energy-efficient than trucks and planes (see image). Vehicles with more storage capacity also have advantages—shipping a large load of apples in an 18-wheeler, for example, is generally more efficient per apple than shipping a few crates in a pickup truck.

What people eat often matters more for climate change than how far food travels. Across the U.S. food supply chain, from farm to retail, transportation accounts for only an estimated 11 percent of GHG emissions. The vast majority of emissions are from food production, particularly livestock production. If Americans followed a plant-based diet one day per week, they could cut GHG emissions more than by following an entirely local diet.9

Local and regional food systems

Farmers Market

Veggies at a farmers’ market in Baltimore.

Buying food directly from farmers can give people an opportunity to learn firsthand where their food comes from. This idea is embodied in the Japanese word teikei, loosely translated as "food with the farmer's face on it." Teikei was the inspiration behind the community supported agriculture (CSA) movement.17

Photo credit: Mike Milli, Johns Hopkins Center for a Livable Future.


Share of CSA produce.

In community supported agriculture (CSA), participants pay up front for a share of the season’s harvest, usually at a discounted rate. Payments at the start of the season help farmers cover the cost of labor and supplies. Participants share in the risks and rewards of farming: If, for example, pests wipe out a tomato crop, they may have to make do with extra kale.

Photo credit: Mike Milli, Johns Hopkins Center for a Livable Future.

Click images for captions

“Local” food may mean different things to different people. It is sometimes defined as food that was produced within 100 or 250 miles of where the consumer lives, or food that is sold directly from a farmer to a consumer (e.g., at a farmers’ market).13

What is the appeal of local food?

Surveys suggest consumers perceive local food as fresher, and like the reassurance of knowing where and how it was produced.14 They may also be drawn to opportunities to support their local economy—buying local can support new jobs and higher incomes in a community.13

For farmers, selling to the mass market often means growing hardy fruits and vegetables, bred to withstand the bumps and bruises of long-distance transport and long periods on supermarket shelves. Selling locally, on the other hand, allows farmers to experiment with crop varieties that may be more flavorful, nutritious, or rooted in local heritage.15

In many cases, however, it is neither realistic nor desirable to source food entirely within 100 or 250 miles. Highly populated, very cold, and very dry places, for example, may need to source food from farther away. 

If local is too limiting, how far should food travel? The idea of a regional food system takes into account the distance needed to produce enough food, with enough variety, and to produce it in ways that are sustainable. Because those distances vary from place to place, the boundaries of a regional food system are not universally defined, though they usually encompass a much larger area than what is considered local (e.g., a multistate area in the U.S. such as the Northeast).16


The following list of suggested resources is intended as a starting point for further exploration, and is not in any way comprehensive. Some materials may not reflect the views of the Johns Hopkins Center for a Livable Future.

For teachers


Academic journal articles




1. Freidberg S. Fresh: A Perishable History. Harvard University Press; 2009.
2. U.S. Census Bureau. State & County QuickFacts. 2010.
3. Peters CJ, Bills NL, Lembo AJ, Wilkins JL, Fick GW. Mapping potential foodsheds in New York State: a spatial model for evaluating the capacity to localize food production. Renew Agric Food Syst. 2008;24(1):72-84.
4. Parsons B. Vermont`s Dairy Sector: Is There a Sustainable Future for the 800 Lb. Gorilla? Vol 1. Burlington, VT; 2010.
5. Timmons D, Wang Q, Lass D. Local foods: estimating capacity. J Ext. 2008;46(5).
6. Hill H. Food Miles: Background and Marketing. Fayetteville, AR; 2008.
7. USDA Economic Research Service. Consolidation in food retailing: prospects for consumers & grocery suppliers. Agric Outlook. 2000;(August):18-22.
8. Pirog R, Van Pelt T, Enshayan K, Cook E. Food, Fuel, and Freeways: An Iowa Perspective on How Far Food Travels, Fuel Usage, and Greenhouse Gas Emissions. Ames, Iowa: Leopold Center for Sustainable Agriculture; 2001.
9. Weber CL, Matthews HS. Food-miles and the relative climate impacts of food choices in the United States. Environ Sci Technol. 2008;42(10):3508-13.
10. Weber CL, Matthews HS. Food-miles and the relative climate impacts of food choices in the United States. Environ Sci Technol. 2008;42(10):3508-3513.
11. Goldstein M. Air Vs. Water: Decision Hinges on Three Factors. 1996.
12. Saunders C, Barber A, Taylor G. Food Miles – Comparative Energy/Emissions Performance of New Zealand`s Agriculture Industry. Christchurch, New Zealand; 2006.
13. Martinez S, Hand M, Da Pra M, et al. Local Food Systems: Concepts, Impacts, and Issues. USDA Economic Research Service; 2010.
14. Food Marketing Institute. U.S. Grocery Shopper Trends. Arlington, VA; 2009.
15. Tropp D, Ragland E, Barham J. Supply Chain Basics: The Dynamics of Change in the U.S. Food Marketing Environment. USDA Agricultural Marketing Service; 2008.
16. Clancy K, Ruhf K. Is local enough? Some arguments for regional food systems. Choices Mag Food, Farm Resour Issues. 2010;25(1).
17. Schnell SM. Food with a farmer’s face: community-supported agriculture in the United States. Geogr Rev. 2007;97(4):550-564.