Sustainlane has determined that Portland, OR is the greenest city. http://www.sustainlane.com/us-city-rankings/ Why? Because of the progressive land use restrictions and urban growth boundaries established in the 1970s. "That's "City-planners in Portland have been thinking green since the 70s, when the rest of the country was still embracing the strip mall. The city enacted strict land-use policies, implementing an urban growth boundary, requiring density, and setting a strong precedent for sustainable development." In addition to "green building" regulations, strong land use regulation that limits sprawling suburban development is necessary to make communities green, as is support for effective infrastructure and public transit. Without these supports for green buildings, all that is going to be developed is more auto-dependent green sprawl.