10 - Austin, Texas
As the gateway to the scenic Texas Hill Country, acreage in Austin that's devoted to green space includes 206 parks, 12 preserves, 26 greenbelts and more than 50 miles of trails.
9 - Chicago, Illinois
This greening of the city continues through the Chicago Green Roof Program. More than 2.5 million square feet of city roofs support plant life — including Willis Tower (formerly called Sears Tower) and the city hall building.
8 - Seattle, Washington
Through an incentive program, residents are encouraged to install solar panels on their homes for energy conservation.
7 - Berkeley, Calif
Berkeley is recognized as a leader in the incubation of clean technology for wind power, solar power, biofuels and hydropower.
6 - Cambridge, Mass.
In 2002, city officials implemented a major climate protection plan and today most city vehicles are fueled by B20 biodiesel or electricity. All new construction or major renovations must meet LEED standards.
5 - Eugene, Oregon
Cycling is the preferred mode of transportation, made possible by the 30 miles of off-street bike paths and 29 dedicated bike routes, which total a whopping 150 miles of smog-free travel throughout the metro area.
4 - Oakland, California
Residents of this port city have access to an abundance of fresh, organic food, much of which is locally sourced. It's also home to the nation's cleanest tap water, hydrogen-powered public transit and the country's oldest wildlife refuge.
3 - Boston, Massachusetts
Boston ranks high among the urban green elite. Sustainability efforts include a "Green by 2015" goal to replace traditional taxi cabs with hybrid vehicles, recycle trash to power homes, use more solar panels, and use more electric motorbikes for transportation.
2 - San Francisco, California
San Francisco is also the first U.S. city to ban plastic grocery bags, a concept that supports its effort to divert 75 percent of landfill waste by 2010.
1 - Portland, Oregon
Declared the most bikeable city in the United States for its 200 miles of dedicated bike lanes, Portland certainly makes forgoing gas-powered travel easy.
