A recent survey tried to identify the "greenest" cities in North America. Produced by the Economist magazine's "intelligence unit," the recent list said San Francisco, Vancouver, New York, Seattle and Denver lead that list. It's based on nine criteria: carbon emissions, energy usage, land use, green buildings, public transportation, water use, waste management, air quality and environmental governance.
Here's for me the interesting piece of data. Citing a United Nations population study, the report offers a view of the continuing urbanization of the planet:
According to the United Nations Population Division, 82% of Americans and 81% of Canadians lived in cities in 2010 and these proportions are set to continue rising, reaching 90% for the US and 88% for Canada by 2050. This is not a new phenomenon. As early as 1955, two-thirds of the populations of both countries lived in cities. Urbanization, though, has now reached a stage where rural America has begun to shrink. In absolute terms, the rural US population dropped by 12% in the last 20 years and the UN predicts it will decline another 14% in the next two decades, even as the overall national population rises. A similar trend is expected to emerge in Canada around 2020.