Portland, Oregon

The recipient of numerous green and sustainability awards, Portland, Oregon, recently earned the highest score in a Popular Science ranking of America's 50 Greenest Cities. The city was also the first in the nation to adopt a Global Warming Action Plan and now half the energy it consumes is renewable. Strict zoning laws, a bike-friendly culture, and a commitment to green buildings have helped Portland avoid some of the sprawl and environmental degradation that's afflicted other western cities.

(Photo: Travel Portland)