Most of the fresh produce you squeeze, thump, and sniff as you peruse the grocery aisles has motored through more states than a Rolling Stones concert tour. Each carrot, cantaloupe and kumquat averages 1,500 miles for privilege of getting tossed into your cart. That is largely due to the fact that some 90 percent of fresh fruits and vegetables are grown in California which, by virtue of its coastal location, is at least a thousand miles away from many of the nation’s major population centers. But some of these so-called "food miles" are international; the typical meal consumed in the U.S. contains ingredients from at least five other countries.

Food miles refers to the total distance food travels from where it’s harvested to where it’s eaten. The concept is used to track the impact of food transportation on the environment. Researchers combine shipping method with number of miles and can come up with a fairly accurate estimate of the amount of greenhouse gases released to get your avocados from San Diego County to New York City. Miles in the air are worse than miles on the ground, because flying pollutes more than driving.

So, how can you tell the distance your food has traveled? Supermarket labels will often display the state or country of origin for some produce. Unfortunately, none show anything akin to a veggie odometer. Unless you travel with a GPS in hand, the best you can do is estimate.

A perfect way to cut down on food miles is to plant a home garden. If you don’t have a green thumb, the next best option is to visit your local farmers market. The average number of food miles for farmers’ market produce is usually between 50 and 100 miles. If you live in an agricultural area, it likely will be less.

Some concerns have been raised recently over whether the environmental impact of farmers market food miles might be more environmentally damaging than supermarket food miles. That theory is based on the assumption that hundreds of farmers, each transporting small quantities of food in gas-guzzling trucks, is worse than the impact of transporting mass quantities of produce over thousands of miles in a single 18-wheeler. Sound research has yet to confirm this idea—particularly for foods that require refrigeration when transported long distances. Such speculation also ignores the fact that aside from racking up fewer food miles, locally grown food is less damaging to the environment in other ways—and better for your health!

Locally grown food is picked ripe from the field the morning of the market and requires little more than a wooden box in the back of a pick-up by way of packaging. By contrast, supermarket produce is typically picked prior to ripening and needs preservatives and loads of packaging to stay fresh and un-bruised during the trip—all of which dumps more chemicals and waste into the environment.

And if you’ve ever eaten a supermarket tomato that tasted like cardboard and was hard enough to pound a nail, you can guess the obvious personal benefits of locally grown produce: it’s more nutritious and it tastes better. So, find a farmers market near you. And consider that a succulent local peach might taste even better if you worked up an appetite by biking there (and thus knocked off the last few food miles of the fruit’s journey).