Top 10 Greenest Cities

San Francisco, Calif., is the greenest city in Northern America, according to Siemens and the Economist Intelligence Unit. Other cities in the top 10 of 27 metros studied included Vancouver, New York, Seattle, Denver, Boston, Washington, Toronto, and Los Angeles. Partnerships with private sector investors helped bump San Francisco to the top of the list, as did exceptionally good waste management and green building intiatives. Cities were rated based on factors such as their environmental governance, land usage, air quality, water usage, and energy.