America just got a little bit greener. Earlier this summer, Aspen, Colo. — John Denver's "sweet Rocky Mountain paradise" — became the first city in the U.S. to launch a comprehensive Meatless Monday campaign. Local restaurants, schools, hospitals, charities and businesses, including the Aspen Valley Hospital, the University of Colorado School of Medicine and Aspen Elementary School, have signed on to promote plant-based meals on Mondays.

For our own health and the health of the planet, the rest of us should go meat-free as well — at least for one day a week.

According to Dawn Shepard, who is heading Aspen's Meatless Monday campaign, Aspen is a very health-conscious community, and residents are also concerned about the environmental costs of meat production. A 2010 United Nations report revealed that meat and dairy products require more resources and cause higher greenhouse-gas emissions than do plant-based foods.

Ms. Shepard says that if everyone stopped eating meat one day each week, it would reduce carbon emissions as much as would taking 25 million cars off the road for a year. Chris Weber, a professor of civil and environmental engineering at Pennsylvania's Carnegie Mellon University, has found that not eating meat and dairy products for one day a week has an even bigger impact on the environment than buying local foods every single day of the year.

In an effort to save the environment and animals, a growing number of people — not just in Aspen but across the country — are swearing off meat, at least on Mondays. A May 23 FGI Research study shows that 50 percent of Americans have heard of the Meatless Monday movement, which was started in Baltimore in 2003 by the Johns Hopkins Bloomberg School of Public Health. That's up from 30 percent just six months earlier. At least 27 percent of consumers who know about the campaign have opted to eat less meat as a result, and a significant percentage of people would like to see Meatless Mondays promoted in restaurants, fast-food chains, supermarkets and cafeterias.

At the rate things are going, they may soon get their wish. This month, the board of commissioners in Durham County, N.C., officially proclaimed Mondays as "Meatless Mondays." Last year, officials in San Francisco and Washington, D.C., passed resolutions urging people in those cities to choose plant-based meals on Mondays. Baltimore City schools have been observing "Meatless Mondays" since 2009, and in February 2010, Manhattan borough president Scott Stringer proposed that all New York City public schools follow suit. Several have followed his recommendation.

This January, Sodexo, a leading food-service provider, began offering a weekly plant-based entrée option to the 900 hospitals and 2,000 corporate and government clients that it serves in North America. Vegetarian Day observations and activities are also taking place in Israel, Australia, the U.K., Finland, Belgium and other parts of the world.

We're off to a good start — especially in Aspen — but the Meatless Monday campaign needs to keep on snowballing throughout the country. Americans eat twice as much meat as the average person worldwide. Not surprisingly, we spend more money on health care than does any other nation. Unlike vegan foods, which are cholesterol-free and generally low in fat and calories, meat is high in saturated fat and cholesterol and contributes to obesity, diabetes, heart disease, stroke, cancer and other life-threatening illnesses.

While going vegan is the best way to save the planet and to save lives — our own and those of animals — people who aren't yet willing to stop eating meat entirely can still help by not eating meat for at least one day a week. If you're already observing Meatless Mondays, try extending your efforts to Tuesdays too. Or help Meatless Monday campaigners reach even more people by telling everyone you know about the initiative. It will help bring us all a bit closer to that "sweet Rocky Mountain paradise."

Heather Moore is a staff writer for the PETA Foundation in Norfolk, Va. Her email is heatherm@petaf.org.