Greenest City: New York City

Named by the Natural Resources Defense Council as a Smarter City for Transportation in 2011 and a Smarter City for Energy in 2010, New York City is following through on Mayor Michael Bloomberg's ambitious PlaNYC. Now in its fourth year, the plan envisions a sustainable future for the city even as its population increases. Under the plan, the city's greenhouse gas emissions will be reduced 30% through a number of initiatives, from building energy efficiency standards to expansion of bicycle commuting lanes. Notable accomplishments in the last year include making Times Square into a pedestrian-friendly causeway, planting thousands of trees and fighting to get hybrid taxis on the streets.