Some of my best memories come from summer road trips with my wife, Ramona. I naturally focus on economic anthropology, i.e., how folks organize, coordinate, and exchange. Differences are huge. They testify to the vitality, viability, and variety we've come to expect from an open society. Here are a few examples.

We twice visited the summer encampments of Earth First!, the Green organization that makes Greenpeace seem moderate. More recently, we toured the Rainbow Family encampments near Jackson, Montana, and met with spokespersons of this leaderless group. After this trip we helped produce a book, Judge Dave and the Rainbow People. It is DC Circuit Judge Dave Sentelle's spectacularly humorous account of his 1987 decision to permit the Rainbows to meet on Forest Service lands.

David Brooks is a writer for the Weekly Standard and the New York Times. He visited Bozeman and Seattle while conducting research for his book Bobos in Paradise. Seattle boasts the mother church of REI, a co-op established by mountain climbers in 1938. Brooks was mesmerized by his experience at REI's new facility. It generated an entire chapter in Bobos and motivated Ramona and me to explore it ourselves. The "store" includes a mountain bike test trail and one of the world's tallest freestanding indoor climbing walls.

We enjoyed this adventure and strongly recommend joining this co-op. It has a huge selection of great products, service, and attitudes -- plus a rebate of about 10 percent at the end of each year. I've been a member for about 40 years. My REI member number is so low the cashiers comment.

Several friends recommended a shopping expedition to The Good Food Store's new building in Missoula. This has grown from a little store smaller than Bozeman's new co-op (where we've long been members) to a full-size grocery store. Like Bozeman's Community Food Co-op, The Good Food Store has grown and prospered since its founding 30 years ago. It offers the culinary analogue to REI's new facility in Seattle. Good Foods is not a co-op but rather a nonprofit community corporation, much like Bozeman's Bridger Bowl ski area. The store offers a wonderful example of both food choice and the dynamism of the market process.

Such stores were the first to bring organic produce and meats to consumers. Now major chains like Albertsons and Safeway feature organics. I celebrate co-ops for expanding consumer choice and demonstrating the power of the market's discovery process.

Many folks dismiss or discount the market's power to identify and satisfy latent or emerging preferences. There was no FDA mandate that a certain percentage of grocers' food must be organic or locally produced. There are no significant tax credits or federal grants for those establishing community co-ops. Rather, the entrepreneurs (social as well as economic) who start co-ops discover a niche and mobilize resources to fill it. In doing so, they allow people to incorporate their conscience into their commerce.

Market exchange permits people with radically differing views to peacefully coexist. Bozeman harbors a substantial number of hard-core vegetarians. Yet they shop peacefully and amicably with rancher and logger meat-eaters who consume vegetables reluctantly, usually as a concession to their physician's advice.

Bozeman is also a national center for teetotaling Seventh Day Adventists. The supermarket accommodates their preference for nonalcoholic beverages, and they shop harmoniously with our friends whose dinners include wine. This peaceful interaction occurs only because all transactions are voluntary.

What if politics governed the stocking of a grocery store? Imagine the fights between vegetarians and meat-eaters; the teetotalers and the wine drinkers; the granola organics who argue against pesticides and the farmers who find chemicals useful; the populists who are strongly opposed to corporate agriculture and those with an interest in these firms; working mothers who want the stores open 24 hours a day, seven days a week, and fundamentalists who believe they should be closed on Sundays (or Saturdays).

Fortunately, most of these decisions have been kept out of the political arena. In markets, whether the enterprise be for-profit, nonprofit, or co-operative, people make decisions and exercise their consciences without imposing their preferences on others through the force of law. Peace, progress, and innovation are the predictable results of a free-market economy.